EGF and breast carcinoma: Interestingly, GPR54 directly complexes with EGFR, and stimulation of breast cancer cells by either EGF or KP-10 regulated the endocytosis of both GPR54 and EGFR.86 This signalling has an opposite effect on breast cancer cells, i.e., it is pro-migratory and pro-invasive in human breast cancer cells.