Different from other tumor-suppressor genes, the decreased protein level of P27 in tumors was mainly due to the degradation mediated by the over-activated SCF complexes rather than DNA mutations.16, 26 In this study, we applied MLN4924 to investigate the functions of P27 as an important substrate of SCF complex in gastric cancer cells. The gene discussed is CDKN1B; the disease is gastric cancer.