Retroviral Gene Transfer of Epidermal Growth Factor Receptor into HL6O Cells Results in a Partial

HL6O cells are devoid of endogenous epidermal growth fador receptor (EGFR). They respond to retinoic acid and undergo terminal granulocytic differentiation. EGFR complementary DNA was introduced into HL6O cells by retroviral gene transfer. Scatchard plot showed that the binding charaderistics are identical to those of A431 cells. HL6O-EGFR cells were estimated to express 34,000 EGFR/cell (Kd 5 nM). The tyrosine phosphorylation upon higand binding is the first step of signal transdudion. The dominant phosphotyrosyl proteins in epidermal growth fador-stimulated HL6O-EGFR cells include a 1 70 kDa protein (EGFR itself), and 1 25 and 53 kDa proteins. The EGFR signal results in the indudion of 92 kDa gelatinase/matrix metalloproteinase in HL6O-EGFR cells, thereby providin