Protein kinase C (PKC) and its inhibitor activities were measured in human coloretal cancer cell line CCL₂₂₉ induced by retinoic acid (RA) and 1, 25-dihydroxyvitamin D₃ (1, 25 (OH)₂VD₃) both for two days and phorbol 12-myristate 13-acetate (PMA ) for six hours. The results showed that total PKC activity was markedly increased after treatment with three inducers (P< 0. 05 ). The cytosolic PKC activities were significantly increased in RA and 1, 25 (OH)₂VD₃ treated CCL₂₂₉ cells (P< 0. 05 ). In PMA-treated cells，the membrane ratio(membrane activity/total activity) was significantly increased (P<0. 01).The levels of PKC inhibitor in cytosolic membrane supernatants after treatment with three inducers were all decreased. Among these three inducers，1，25 (OH)₂VD₃ caused significantly difference compared with control. The results implied that PMA translocates PKC from the cytosolic to membrane fraction，PKC and its inhibitor in RA，1，25 (OH)₂VD₃ and PMA-induced cells are in different relatively parralel relationship.