Fetal calf serum and epidermal growth factor prevent the inhibitory action of a chalone-like growth inhibitor for Ehrlich ascites mammary carcinoma cells in vitro.

A growth inhibitor for the Ehrlich ascites mammary carcinoma, purified from bovine mammary gland, is antagonized by very low concentrations of epidermal growth factor (2-16 X 10(-10) M) or fetal calf serum (0.001-0.1%). Thus, epidermal growth factor and the compounds in fetal calf serum have the same effect as earlier described for insulin and proinsulin [1-3].