Two series of evidence suggest that CDKN1B behaves as a classical TSG: LOH at chromosome 12p13, encompassing the CDKN1B locus, is frequently found in breast, prostate, and ovarian cancers (9, , , , –14), and reduced CDKN1B protein is significantly associated with high-grade and high-stage disease in those tumors [reviewed in (14)]. Here, CDKN1B is linked to ovarian cancer.