Catechins induced mitochondrial trans-membrane potential collapse, cytochrome C loss and ROS production in NB4 cells. (A) The inhibitory effect of NB4-R1, NB4-R2 and NB4 cells in response to ATRA (1 μM), As2O3 (1 μM), EGCG (100 μM), ECG (100 μM), EGC (100 μM) and Catechins (100 μM) treatment for 24 and 48 h. (B) Growth inhibition of NB4 cells was significantly abrogated by pan-caspase inhibitor ZVAD-FMK (50 μM). **P <0.01 comparing with the Catechins group. (C) The mitochrondrial trans-membrane potential was decreased in NB4-R1, NB4-R2 and NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. The numbers below the scatter plots represented the percentage of Rh123 low cells. (D) The mitochondrial cytochrome c was accordingly decreased in NB4-R1, NB4-R2 and NB4 cells treated with 100 μM and 200 μM Catechins for 24 h. (E) ROS generation by Catechins in NB4-R1, NB4-R2 and NB4 cells. DCF-derived fluorescence in untreated and in those treated for 2 h with 200 μM Catechins was shown. *P < 0.05, **P < 0.01, ***P < 0.001 comparing with the untreated cells.