Calmodulin antagonists decrease the binding of epidermal growth factor to transformed, but not to normal, human fibroblasts

Four psychoactive agents which inhibit calmodulin activity were used to study their effect on the binding of epidermal growth factor (EGF) to normal and simian-virus-40-transformed human fibroblasts (WI38). These calmodulin antagonists decreased the binding of ¹²⁵I-labelled EGF to the transformed, but not to the normal, cell in a dose-dependent manner. The mechanism of this effect appears to be due to a decrease in the apparent affinity of the plasma-membrane EGF receptor for the EGF molecule.