Inhibitory Function of p21~Cip1/WAF1 in Differentiation of Primary Mouse Keratinocytes Independent of Cell Cycle Control

摘要

The cyclin-dependent kinase inhibitor p21~Cip1/WAF1 has been implicated as an inducer of differentiation. However, although expression of p21 is increased in postmitotic cells immediately adjacent to the proliferative compartment, its expression is decreased in cells further along the differentiation program. Expression of the p21 protein was de- creased in terminally differentiated primary keratinocytes of mice, and this occurred by a proteasome-dependent pathway. Forced expression of p21 in these cells inhibited the expression of markers of terminal differentiation at both the protein and messenger RNA levels.