Cyclin-Dependent Kinase 4 Levels Affect the Number of Hair Follicle Stem Cells in Mouse Epidermis

The study investigated the role of Cyclin-dependent kinase 4 (CDK4) in hair follicle stem cells and skin tumorigenesis using a mouse model. It was found that overexpression of CDK4 in mouse epidermis led to a 4-fold decrease in keratinocyte stem cells (KSC), while CDK4 deletion resulted in a 4-fold increase in KSC. This suggests that CDK4 levels influence the balance between stem cells and transit amplifying cells, affecting susceptibility to papilloma development. The findings indicated that CDK4 expression affects the asymmetric division of KSCs, with potential implications for understanding skin cancer progression.