Role of INK4a/Arf locus-encoded senescent checkpoints activated in normal and psoriatic keratinocytes.

During malignant transformation in skin, epidermal keratinocytes (KCs) frequently acquire the capacity to by-pass cellular senescence, a response that normally limits their unrestricted proliferation. Despite growing interest in the role for senescence during aging of skin and cutaneous carcinogenesis, little is known regarding regulation of three proteins encoded by the INK4a/ARF locus (p12, p14(ARF), p16) in KCs. In this study, several molecular pathways are explored using cultured KCs and KCs freshly isolated from psoriatic plaques.