Experimental strategy. (A) Purification strategy for samples used to generate these data sets. Baso, basophilic erythroblast; BFU-E, burst-forming unit-erythroid; BFU-MK, burst-forming unit-megakaryocyte; CFU-E, colony-forming unit-erythroid; CFU-MK, colony-forming unit-megakaryocyte; MEP, megakaryocyte-erythrocyte precursor; MK, megakaryocyte; Ortho, orthochromatic erythroblast; Poly, polychromatic erythroblast; Pro, proerythroblast. Purification strategies for MEPs, the MK lineage in bulk, the erythroid lineage in bulk, and individual erythroid stages are indicated. (B) Strategy to identify differentially retained introns between pairs of samples using IRFinder.