MAPK3 and cancer: Treatment of cancer cells with U0126, a selective MAPK/ERK kinase1/2 (MEK1/2) inhibitor that blocks ERK1/2 phosphorylation41, or with cetuximab, a humanized monoclonal antibody to EGFR42, inhibited J1.1 cell exosome-induced HSC3 cancer cell proliferation (Fig. 5a) and invasion (Fig. 5b), respectively.