STAT3 and Ewing sarcoma: To examine if STAT3 plays a role in Ewing sarcoma chemoresistance, we depleted endogenous STAT3 in MHH-ES-1 cells and found STAT3 depletion didn’t affect SN-38-induced Akt-pT308 and ERK-p42/p44 (Supplementary Fig. 8h,, i).