A link between development of human cancers and cellular pathways where the retinoblastoma protein (pRb) has a major role is well established.1, 2 One of the frequent events associated with human tumour progression is abnormality in the pathway that links pRb, p16INK4A, cyclin D1 and Cdk4 (cyclin-dependent kinase 4).3 Cdk4 along with its activating cyclin partner D1 has a key role in cell cycle control.4, 5 The naturally occurring inhibitor of Cdk4-cyclin D1, p16INK4a (p16), is a tumour supressor protein. This evidence concerns the gene RB1 and neoplasm.