Srsf2^P95H/+ expression does not substantially sensitize to splicing inhibitors but does enable accumulation of human MDS/MPN-relevant mutations. (A) Response of Hox-immortalized cells of the indicated genotypes to the spliceosome inhibitors spliceostatin A (left) and pladienolide B (right) with calculated 50% inhibitory concentration (IC₅₀). (B) Analysis of somatic mutations accumulating in the BM of moribund R26-CreER Srsf2^P95H/+ (n = 2) and an hScl-CreER R26eYFP Srsf2^P95H/+ animal (n = 1) by exome capture analysis. Mutations are defined against the list of most frequently occurring mutations in human MDS/MPN.