The effect of Catechins treatment on growth and apoptosis of human leukemia cell lines. (A) IC50 results obtained from MTT assay in leukemia cell lines treated with Catechins at 24 h. The IC50 values of NB4-R1, NB4-R2 and NB4 cells were below 125 μM. (B) The growth inhibition of NB4-R1, NB4-R2 and NB4 cells treated with Catechins for 24 and 48 h. Reduced cell viability were detected in APL cell lines from 50 μM Catechins. (C) Characteristic apoptotic cells were present in NB4-R1, NB4-R2 and NB4 cells treated with 100 μM or 200 μM Catechins for 24 h. (D) Detection of apoptotic cells by Annexin V-FITC/PI double staining in NB4-R1, NB4-R2 and NB4 cells treated with 100 μM Catechins for 24 and 48 h. Catechins treatment increased the percentages of Annexin-V+/PI- cells (lower right quadrant) and Annexin-V+/PI + cells (upper right quadrant). (E) Contribution of nuclear DNA content in NB4-R1, NB4-R2 and NB4 cells treated with 100 μM Catechins for 24 h and 48 h. Significantly increased sub-G1 cells were observed. *P < 0.05, **P < 0.01, ***P < 0.001 comparing with the untreated cells.