PDGFRB and cancer: Even though patients may initially benefit from these vertical combination therapies, cancers can come back with activated alternative pathways such as RAS signaling or the receptor tyrosine kinases PDGFR, MET (hepatocyte growth factor receptor) and ERBB3 (V-Erb-B2 Avian Erythroblastic Leukemia Viral Oncogene Homolog 3), or the AKT signaling pathway (45, 46).