Epidermal growth factor-like activity and epidermal growth factor-receptors in human primary breast cancer.

Ligands binding to epidermal growth factor-receptors (EGF-Rs) as epidermal growth factor-like activity (EGF-like activity), along with EGF-R levels, were determined from human primary breast cancer samples. Receptor analysis revealed a single class of high affinity binding sites. Ng/mg protein EGF-like activity quantities were measured in cytosols, and were inversely correlated with EGF-R contents (p < 0.01), estimated by two-point assays.