MDA-MB-468 human breast cancer cells lack estrogen receptors, overexpress epidermal growth factor (EGF) receptors, and are growth inhibited by EGF. We show that treatment of MDA-MB-468 cells with EGF leads to inhibition of cell proliferation, fragmentation of DNA into nucleosomal oligomers, and the development of apoptotic morphology. This treatment is associated with increased expression of c-myc, c-fos, jun family members, and transforming growth factor beta 1 mRNA and with partial proteolytic cleavage of poly(ADP-ribose) polymerase and lamin B. The observation that EGF can mediate apoptosis in EGF receptor-overexpressing cells has important implications for clinical efforts directed at the EGF receptor.