Ex vivo cytotoxicity and protein degradation by PROTACs in patient-derived xenograft ALL cells. (A-F) Response of multiple ALL xenografts of different genotypes to PROTACs in stromal cell–based ex vivo cytotoxicity assays. (G) Ex vivo phosphoflow analysis of xenograft SJBALL021415 cells harvested from bone marrow of NSG mice. (H) Ex vivo dose-dependent degradation of JAK2 and GSPT1 protein by compound 8 in xenograft SJBALL021415 cells. Cmpd, compound.