Fig 1: Involvement of ubiquitin and IAP in SNIPER(ABL)‐39‐induced degradation of BCR‐ABL protein. (a) Turnover of BCR‐ABL proteins after SNIPER(ABL)‐39 treatment. K562 cells were treated with 10 μg/mL of cycloheximide (CHX) in the presence or absence of 30 nM of SNIPER(ABL)‐39 for the indicated periods. Numbers below the panels represent BCR‐ABL/GAPDH, Cyclin B1/GAPDH and MCL‐1/GAPDH ratios normalized by time 0 control as 100. Data in the graphs are means ± SD (n = 3). (b) Expression of Bcr‐Abl mRNA in K562 cells. Cells were incubated with the indicated concentration of SNIPER(ABL)‐39 for 6 h. Expression levels are relative to vehicle treatment, which was arbitrarily set to 1. Data in the bar graph are means ± SD (n = 3). (c) Effect of ubiquitin activating enzyme inhibitor MLN7243 on protein knockdown activity of SNIPER(ABL)‐39 in K562 cells. Cells were incubated with the indicated concentration of SNIPER(ABL)‐39 and/or MLN7243 for 6 h. (d) Silencing of both cIAP1 and XIAP expression attenuates SNIPER(ABL)‐39‐dependent BCR‐ABL protein degradation. In K562 cells, endogenous cIAP1 and/or XIAP were depleted by shRNA for 72 h. Then cells were treated with the indicated concentration of SNIPER(ABL)‐39 for 6 h. Numbers below the ABL panel represent BCR‐ABL/GAPDH, BCR‐ABL/β‐tubulin, or BCR‐ABL/β‐actin ratio normalized by vehicle control as 100.