Endogenous ligands for the epidermal growth factor receptor in human breast tumors do not interfere in an epidermal growth factor receptor radioligand binding assay.

Ligands for the epidermal growth factor receptor (EGFR) (e.g. EGF and transforming growth factor alpha, TGFα) may be included in membrane preparations from human breast tumors, either complexed or not to EGFR. Assessment of EGFR in human placental membranes (HPM) after preincubation with human EGF (hEGF) or human TGFα (hTGFα) indicated that the presence of these ligands in a membrane preparation did not affect the apparent number of binding sites, but only resulted in an increased apparent dissociation constant (Kd).