It has also been shown that Id1 and Id3 overexpression correlates with loss of CDKN2A expression in different tumours (Polsky et al, 2001; Lee et al, 2003), suggesting that in some settings Id1/3-induced cell proliferation is mediated through the inactivation of the CDKN2A-pRb pathway. Here, ID1 is linked to neoplasm.