The keratinocyte, a specialized epidermal cell that synthesizes keratin, is the major cell type of the epidermis, making up about 90% of epidermal cells. Keratinocytes originate in the basal layer from the division of keratinocyte stem cells. They are pushed up through the layers of the epidermis, undergoing gradual differentiation until they reach the stratum corneum where they form a layer of dead, flattened, highly keratinized cells called squamous cells. This layer forms an effective barrier to the entry of foreign matter and infectious agents into the body and minimises moisture loss.

174H.64

• a novel marker for basal (stem) cells of mammalian stratified squamous epithelia and squamous cell carcinomas. PMID: 2468409

Calmodulin

• a calcium binding protein that is expressed throughout the living layers of the epidermis. PMID: 11407979

Calmodulin-like skin protein

• a new marker of late keratinocyte differentiation with a role distinct from calmodulin. PMID: 11407979

CD24 (heat stable antigen, nectadrin)

• a novel keratinocyte differentiation marker, is preferentially expressed in areas of the hair follicle containing the colony-forming cells. PMID: 9004038

CD34

• a specific marker of bulge cell keratinocytes in the cutaneous epithelium. PMID: 12648211

CD98

• may be considered as a marker of transient amplifying human keratinocytes. PMID: 16097038

Epidermal calcium-binding protein (ECaBP )

• a marker of early differentiation of basal layer keratinocytes of rats. PMID: 7683255

Fibronectin

• a cognate keratinocyte antigen identified by mass spectrometry. PMID: 12644568

Filaggrin

• a sensitive keratinocyte differentiation marker of maturation of normal epidermis and provides a new tool for the study of differentiation of the surface epithelium in skin diseases. PMID: 3125677

G6K12

• recognizes a plasma membrane-anchored glycoconjugate which is specific for differentiated keratinocytes. PMID: 7686225

GP37

• a sensitive marker of epidermal keratinocyte differentiation and may be useful in skin pathology and in in vitro studies. PMID: 2426893

gp80

• a glycoprotein that is expressed by growth-arrested human keratinocytes or as part of the terminal differentiation program. PMID: 7665923

hKPRP (human gene encoding keratinocyte proline-rich protein)

• an epidermal marker expressed in stratified squamous epithelia and has a potential role in keratinocytes differentiation. PMID: 16297201, PMID: 16297201

ICAM-1

• keratinocyte activation marker. PMID: 7747530

Involucrin

• a recently recognized structural component of mature squamous epithelial cells, is a marker for keratinocyte differentiation. PMID: 6392430, PMID: 1356394
• One useful marker for an early stage in the pathway of terminal differentiation. PMID: 6345687

Keratinocyte transglutaminase

• Keratinocyte differentiation marker and member of an extended family. PMID: 11485391, PMID: 1364041
• may be useful in evaluating the degree of differentiation in benign and malignant oral epithelial proliferation. PMID: 1974551

K1/K10 Keratin

• one of the earliest characterized events in keratinocyte differentiation is the coordinate induction of a pair of keratins specifically expressed in suprabasal cells, keratin 1 (K1) and keratin 10 (K10). PMID: 7693721

K5/K14 Keratin

• markers for basal keratinocytes. PMID: 2483836
• K14 is a marker of stratifying epithelia. PMID: 2480909

K3/K12 Keratin

• markers for corneal-type differentiation. PMID: 2483836

K6/K16/K17 Keratin

• markers of keratinocyte hyperproliferation in psoriasis in vivo and in vitro. PMID: 7577575, PMID: 2483836

KL3

• recognized a keratinocyte membrane antigen implied in the epidermal differentiation process. PMID: 2578699

KPRP

• expressed by fetal dermal keratinocytes during late gestation and is a new marker of maturing epidermis during fetal skin development. PMID: 12668678

Laminin-5

• a cognate keratinocyte antigen identified by mass spectrometry. PMID: 12644568

Minoxidil Sulfotransferase

• an early marker of human keratincyte differentiation. PMID: 1349030

MRP-8

• a marker of hyperproliferative or abnormal keratinocyte differentiation. PMID: 9325272, PMID: 8959347

MTS24

• a cell-surface marker that identifies a new reservoir of hair follicle keratinocytes with a proliferative capacity and gene expression profile suggestive of progenitor or stem cells. PMID: 16818453

NGAL (Neutrophil gelatinase-associated lipocalin)

• a 25-kDa protein initially isolated from the specific granules of human neutrophils, is a marker for dysregulated keratinocyte differentiation in human skin. PMID: 12473066

p63

• corneal keratinocyte stem cells marker. PMID: 15316140

Plectin

• a cognate keratinocyte antigen identified by mass spectrometry. PMID: 12644568

rSQ20 and hSQ16

• new markers of squamous cell differentiation. PMID: 1348511

SKALP

• overexpressed in psoriatic lesions as compared to the normal epidermis, and is a marker of hyperproliferative keratinocyte differentiation. PMID: 8959347

SPR1 (small proline-rich protein-1)

• a putative squamous cell marker. PMID: 1627333

SPRR1

• squamous-cell marker. PMID: 10783132

SPRR1A

• Keratinocyte terminal differentiation marker. PMID: 9733767, PMID: 8325635
• specifically expressed during keratinocyte terminal differentiation. PMID: 9826750

SPRR1B (small proline-rich protein 1B)

• a squamous differentiation marker. PMID: 12091247, PMID: 11313996

SPRR2A

• keratinocyte terminal differentiation marker. PMID: 10413601, PMID: 9826750, PMID: 8325635

SQM1 protein

• a useful marker for the study of squamous differentiation and metaplasia of HBE cells. PMID: 9509300

Thrombomodulin (TM)

• a differentiation marker for spinous layer keratinocytes and is a useful tool in histopathological study of epithelial tumours. PMID: 8881658

Tob

• stably expressed in primary human keratinocytes and it is specifically expressed in the basal layer of in vivo epidermis. PMID: 16445768

Other Markers

• The use of these fluorescent probes provides a reliable tool to detect the early signs of damage in keratinocyte cultures. PMID: 11132730
• PNA-reactive gps are late highly IFN-gamma-sensitive markers of keratinocyte differentiation, drastically modulated through selective isoforms of PKC. PMID: 9444384
• Pemphigoid, pemphigus and desmoplakin as antigenic markers of differentiation in normal and tumorigenic mouse keratinocyte lines. PMID: 2691098
• Monoclonal antibodies: cell surface markers for canine keratinocytes. PMID: 2444143
• Free sterol metabolism and low density lipoprotein receptor expression as differentiation markers of cultured human keratinocytes. PMID: 2443512
• Monoclonal antibody analysis of keratin expression in epidermal diseases: a 48- and 56-kdalton keratin as molecular markers for hyperproliferative keratinocytes. PMID: 6201492
• Markers of epidermal differentiation expressed by rat keratinocytes cultured by a modified feeder layer technique. PMID: 6199206