Abstract: BACKGROUND ＆ AIM： To study the transforming effects of genistein on BALB/c-3T3 cells. MATERIAL AND METHODS： We used the improved BALB/c-3T3 cell transformation assay to observe the transformation of cells treated by: GEN, B[a]P(10 μmol/L)＋ GEN and MCA(0.2 μg/ml)＋TPA(0.1 μg/ml)＋GEN，at the same time, to detect mutant P53 and PTK activity .RESULTS: When GEN ≥30 μmol/L ,the transforming frequency of BALB/c-3T3 cells was significantly increased compared with Contnol(DMSO 0.5 ％)(P<0.01).The transforming frequency induced by B[a]P(10 μmol/L)＋GEN(30 μmol/L)was much higher than that by B[a]P(10 μmol/L). Expression of mutant P53 was also increased in the group treated by B[a]P(10 μmol/L)＋ GEN(30 μmol/L), B[a]P(10 μmol/L)and GEN(30 μmol/L)However，GEN≥30 μmol/L could inhibit the cell transformation induced by MCA＋TPA;PTK activity also decreased with increasing the dose of GEN. CONCLUSION: Our results suggested that GEN could induce cell transformation itself,on the other hand,it could also inhibit cell transformation under certain conditions.

Key words: genistein, P53, PTK, cell transformation