We have previously demonstrated that epidermal growth factor (EGF) can serve as a potent mitogen for 3T3 cells. We have now selected variant 3T3 cell lines unable to respond to EGF, in order to define cellular events unique to the EGF response and to distinguish which of these events are necessary and which are merely correlative to mitogenesis. By simultaneously treating cells with EGF and colchicine, we eliminated those cells stimulated by EGF to enter mitosis. Of the eight clonal EGF nonresponder variants selected by this procedure, none retains a functional EGF receptor. The EGF nonresponsive va-riant lines still retain the ability to respond to other mitogens.

Variants of 3T3 cells lacking mitogenic response to epidermal growth factor.