These authors expressed a chimeric receptor containing the β4 cytoplasmic domain in MDA-MB-435 breast cancer cells and showed that the β4 chimera was tyrosine phosphorylated upon stimulation with hepatocyte growth factor (HGF), but did not enhance HGF-induced Akt and ERK1/2 phosphorylation45. Here, MAPK3 is linked to breast carcinoma.