In the vast majority of cases, SKP2 overexpression inversely correlates with p27KIP1 expression (Nakayama and Nakayama, 2006; Frescas and Pagano, 2008), which is consistent p27KIP1 being a key target of SKP2 and to be rarely mutated in cancer (Chu et al., 2008). Here, CDKN1B is linked to cancer.