HSP90 client protein AKT, but not BTK, is essential for CLL viability. (a) CLL cells were transfected with siRNA against AKT, BTK, both or non-targeting siRNA (NT). Efficiency of siRNA knockdown was assessed by western blot. One of six representative case is shown. GAPDH, western loading control. (b, c) The abundance of the intended target, BTK, AKT or both was quantified by NIH ImageJ. (d) Efficiency of siRNA knockdown in the presence of NKTert co-culture. (e, f) Quantification of western blot shown in (d). (g, h) Effects of siRNA on CLL cell viability. (d) Effects of siRNA on CLL cell viability in the presence of NKTert co-culture *P<0.05; **P < 0.01; ****P < 0.0001; ns, not significant.