The MNF at Sphase of cells is obviously lower than at G1.This result suggests that most of the micronucleated cells att G1 phase do not enter Sphase and micronucleus rarely form at S phase of cells.

• S期细胞的MNF校G1期有极显著的下降，这提示大部分G1期的微核细胞不能进入S期，使细胞增殖中止，这可能是抗癌药物杀伤肿瘤细胞的机制之一。