Recently, we and others have shown that tumor suppressors, such as those encoded by the p53 gene and the Ink4a/Arf locus, oppose reprogramming and limit the efficiency of the process (Banito et al., 2009; Hong et al., 2009; Kawamura et al., 2009; Li et al., 2009; Marión et al., 2009; Utikal et al., 2009; Zhao et al., 2008). Here, CDKN2A is linked to neoplasm.