FUT4 and acute promyelocytic leukemia: Gefitinib monotherapy did not induce APL cell differentiation (Figures 3A–D); however, the combined therapy of gefitinib plus ATRA and ATO enhanced APL cell differentiation, measured by the surface expression of the myeloid differentiation markers CD11b, CD11c, CD15, and CD16 (Figures 4A–L and S6).