Pomalidomide treatment leads to selective targeting of the transcription networks modulating erythropoiesis and globin switching. (A) qRT-PCR of the main regulators of globin synthesis. The data are shown as the mean fold difference of DMSO ± SEM (N = 5): BCL11A (***P = .0004), SOX6 (**P = .0141), GATA1 (**P = .0113), KLF1 (**P = .0142), LSD1 (**P = .0051), IKZF1 (n.s. P = .1832), MI2B (n.s. P = .7901), GATA2 (n.s. P = .7667), HDAC1 (n.s. P = .1363), and CoREST (n.s. P = .1125). (B-D) Protein lysates from DMSO and pomalidomide-treated cells were collected at day 4 and day 11 of differentiation. The main transcription and chromatin remodeling factors involved in globin switching were investigated by immunoblot assays and grouped based on their expression patterns after pomalidomide treatment (N = 3): (B) IKZF1 (Ikaros), BCL11A, and SOX6 have reduced levels throughout the duration of culture. (C) GATA1, KLF1, and LSD1 display decreased expression early, but then normalize as differentiation progresses. (D) GATA2, CoREST, and HDAC1 are unaffected by pomalidomide. (E) Quantification of immunoreactive bands normalized to glyceraldehyde 3-phosphate dehydrogenase (GAPDH). (F) Western blot for IKZF1 in cells that were dosed with DMSO, Pom 1μM, MG132 5μM, or a combination of Pom 1μM and MG132 5μM for 1, 4, and 8 hours. (G) Cultures were treated with DMSO, Pom 1μM, epoxomicin 1μM, or a combination of Pom 1μM and epoxomicin 1μM for 8 hours, and then immunoblotted for IKZF1. (H) At day 2 and day 4 of differentiation, cells were dosed with indicated treatments for 4 hours. Western blot of BCL11A and IKZF1.