RAF1 and nasopharyngeal carcinoma: ERK1/2 separates from the RAS/RAF/MEK/ERK1/2 complex and phosphorylates multiple kinases and transcription factors, such as transformation specific-1 (ETS-1), activator protein 1 (AP-1), nuclear factor kappa-B (NF-κB), and c-Myc.79,80 In the p38/MAPK pathway, mitogen-activated protein kinase–kinase 6 (MAP2K6) overexpression is associated with radiotherapy resistance and unfavorable prognosis in NPC patients.81 The protein kinase (PAK1) is supposed to phosphorylate RAF1 at serine 338 and MEK1 at serine 298, leading to MAPK activation.82