MAPK8 and Ewing sarcoma: Considering previously STAT6 Ser phosphorylation by TBK144, ERK45, or JNK46 has also been reported to differentially regulate STAT6 transcriptional activity in addition to STAT6 Tyr phosphorylation, and chemotherapy-induced ERK activation in Ewing sarcoma (Fig. 1), we also examined if chemo-induced ERK activation regulates chemoresistance through STAT6 Ser phosphorylation.