CD274 and Hodgkins lymphoma: To determine whether increased survival and proliferation of the HL cells in response to the PD-L1 antibody is linked to the MAPK signaling molecules, we tested the phosphorylation of both P38- and ERK–MAPK (p-P38 and p-ERK) in the control IgG1 isotype or anti-PD-L1-treated HL lines.