Evidence for contribution to a cancer phenotype through haplo-insufficiency has recently been obtained for a number of loci, including CDKN1B (p27Kip1) [61,62], TP53 (p53) [63], DMP1 [64], PTEN [65], APC [66] and NKX3.1 [67]. This evidence concerns the gene CDKN1B and cancer.