PDGFRB and leukemia: Since several of the most artemisinin-sensitive leukemias we tested harbor FLT3/ITD and/or MLLr mutations, both known to elevate FLT3 signaling, and since multiple other kinases are mutated or overexpressed in acute leukemias, we tested three multi-kinase inhibitors – MID (targeting FLT3, cKit, PDGFR) [40], LES (targeting FLT3, JAK2, TrKA/B/C) [41, 42], and SOR (targeting FLT3, VEGFR, PDGFR, RAF) [43, 44] – in combination with AS or ART-838.