AP1 Transcription Factors in Epidermal Differentiation and Skin Cancer

Figure 1

MAPK and AP1 transcription factor control of gene expression. The p38δ MAPK cascade that controls the expression of differentiation-associated genes in epidermis is depicted [10]. The three kinases of the MAPK module include MEKK1, MEK3, and p38δ MAPK. A differentiation stimulus activates upstream regulatory proteins, in this case novel protein kinase c (nPKC) and the Ras small GTPase. These events lead to phosphorylation and activation of MEKK1 which phosphorylates MEK3 which phosphorylates p38δ MAPK. Ultimately p38δ MAPK increases AP1 transcription factor expression and activity and the AP1 transcription factors bind to the response element on the target gene promoter to increase transcription.