(A) K562 and KCL22 cells were transfected with the miR-140-5p mimic or mimic-NC for 48 h, followed by qRT-PCR to assess miR-140-5p expression in both cell lines. ***P < 0.001 vs mimic-NC. (B) K562 and KCL22 cells were transfected with either the miR-140-5p mimic or mimic-NC for 12, 24, 48 and 72 h, and CCK-8 assay was performed to detect the cell viability. **P < 0.01 vs mimic-NC. (C) K562 and KCL22 cells were treated as in (A), flow cytometry detected cell apoptosis. Right panel shows the apoptosis rate of three independent experiments.**P< 0.001 vs mimic-NC. (D) K562 and KCL22 cells were treated as in (A), and western blotting was done to detect expression levels of BAX and BCL-2 proteins. β-actin was used as an internal control. Bottom panel shows densitometric analysis of three independent experiments. **P<0.01, ***P<0.001 vs mimic-NC.