['In this study, we explored the functional roles of microRNA-144 (miR-144) upregulation and downregulation in human acute lymphoblastic leukemia (ALL).', 'Gene expression of miR-144 was examined by qRT-PCR in both ALL cell lines and T-leukemic cells of ALL patients. In ALL cell lines Molt-3 and Jurkat cells, miR-144 was either upregulated or downregulated through lentiviral transduction. The subsequent effects of miR-144 upregulation or downregulation on ALL proliferation, cell-cycle transition, and in vivo xenograft were assessed. Possible downstream target of miR-144, human formin-2 (FMN2), was assessed by dual-luciferase activity assay, qRT-PCR and western blot. FMN2 was then overexpressed in miR-144-upregulated Molt-3 and Jurkat cells to assess its effect on miR-144 induced tumor suppression on ALL proliferation and cell-cycle transition.', 'MiR-144 was significantly downregulated in both ALL cell lines and T-leukemic cells of ALL patients. Lentiviral transfection successfully induced miR-144 upregulation or downregulation in Molt-3 and Jurkat cells without affecting cell viability. Functional assays demonstrated that miR-144 upregulation suppressed ALL proliferation and cell-cycle transition in vitro, and growth of Jurkat xenograft in vivo, whereas miR-144 downregulation had no functional effect on ALL development. Multiple approaches confirmed that FMN2 was the downstream target of miR-144 in ALL. Finally, overexpressing FMN2 reversed the inhibitory effects of miR-144-upregulation on ALL proliferation and cell-cycle transition.'] Does microRNA-144 regulate cancer cell proliferation and cell-cycle transition in acute lymphoblastic leukemia through the interaction of FMN2?