p57 / Kip 2 (or CDKN 1C) is a potent tight binding inhibitor of several G1 cyclin complexes, and is a negative regulator of cell proliferation. The gene encoding human p57 / Kip 2 is located on chromosome 11p15.5, a region implicated in both sporadic cancers, Wilm's tumor, and Beckwith Wiedemann syndrome (BWS, a cancer syndrome) making it a tumor suppressor candidate. BWS is characterized by numerous growth abnormalities and an increased risk of childhood tumors. Several types of childhood tumors including Wilms' tumor, adrenocortical carcinoma and rhabdomyosarcoma display a specific loss of maternal 11p15 alleles, suggesting that genomic imprinting plays an important part. This region also contains two other imprinted genes, insulin like growth factor II (IGF II) and H19, both of which seem to be implicated in adrenal neoplasms.