In order to clarify the action of the bcr-abl, a growth factor dependent human leukemic cell line (HSM-911) was transfected with p210bcr-abl or bcr-v-abl by electroporation. The cells transfected with bcr-v-abl, but not the cells transfected with p210bcr-abl, became growth factor independent. Some clones of the cells transfected with p210bcr-abl demonstrated cellular maturation (nuclear segmentation, becoming positive for naphthol ASD chloroacetate esterase, the disappearance of CD34 expression and the appearance of glycophorin A and CD10 expression). Moreover, these clones transfected with p210bcr-abl demonstrated apoptosis (increased expression of Fas and DNA ladder formation suggesting apoptotic DNA fragmentation). These findings demonstrated the different actions of p210 bcr-abl and bcr-v-abl, the former of which gave the cells the characteristics of maturation like the cells from chronic myelogenous leukemia, and the latter of which rendered the cells grow autonomously.