p21Waf1 is required for complete oncogenic transformation of mouse embryo fibroblasts by E1Aad5 and c-Ha-ras oncogenes

► We compared E1A/c-Ha-Ras-transformed wild-type and p21Waf1-null MEFs. ► p21−/− cells are not completely transformed, retain fibroblast-like morphology. ► p21−/− cells have actin stress fibers and show reduced migration and invasion. ► Actin depolymerization correlates with partial cytoplasmic retention of p21Waf1. ► Cytoplasmic p21Waf1 is likely to be required for complete transformation of MEFs.