CDKN1B and neuroblastoma: Overexpression of cyclin D1 produces shorter G1 phase and less dependency on growth factors, resulting in abnormal proliferation.41 Foskolou et al20 recently demonstrated that PROX1 was sufficient to decrease Cdc25A and induce p27-Kip1 but not p21-Cip1 or p53, negatively regulating neuroblastoma carcinogenesis.