Varying responses of PML-RARA mutants to arsenic treatment were validated in hematopoietic cells. (A) Flow cytometry analysis of purified normal human CD34⁺ hematopoietic stem cells (HSCs). (B) Lentiviral-mediated delivery of control vector, wild-type PML-RARA (PR-WT), an arsenic-resistant mutant (A216T), or a nonresistant mutant (S220G) was performed in CD34⁺ HSCs. (C) U937 cells were transduced with lentiviral constructs expressing PR-WT, A216T, or S220G mutants. Infected cells were treated with or without 1 μM of As₂O₃ for 16 hours. Protein levels in the soluble and insoluble fractions from whole-cell lysates were detected by immunoblotting using the indicated antibodies.