The role of DNA damage response proteins p53 and p21(CIP1/WAF1) in aneugenesis and clastogenesis was investigated in telomerase immortalized diploid human fibroblasts using siRNA suppression of p53 and p21(CIP1/WAF1).     ///    Micronuclei were predominantly of clastogenic origin in control cells regardless of p53 or p21(CIP1/WAF1) expression.     ///    "Furthermore, our current results support this role for p21(CIP1/WAF1) since suppression of p21(CIP1/WAF1) caused a decrease in aneuploidy induced by arsenite, suggesting that p21(CIP1/WAF1) plays a role in mitotic exit.. "    ///    Suppression of p21(CIP1/WAF1) like p53 suppression decreased the fraction of MN with centromeric DNA. 