Tsuda et al. investigated pRb/cyclin D1/p16INK4A/CDK4-pathway alterations in endometrioid-type endometrial carcinomas and hypothesized that aberrant expression of p16INK4A and CDK4 proteins constituted an early event during endometrial tumorigenesis (Semczuk and Jakowicki, 2004). Here, CDK4 is linked to endometrial carcinoma.