PDGFRB and neoplasm: For example, overexpression of huntingtin-interacting protein 1, an adaptor for clathrin coat assembly, alters epithelial growth factor receptor (EGFR) trafficking during tumour development; mutant variants of hepatocyte growth factor receptor (HGFR) exhibit increased endocytosis, resulting in enhanced tumour progression; and ras protein (RAS)-induced macropinocytosis of platelet derived growth factor receptor beta can promote tumour progression5, 6.