Cytotoxicity of single-agent and combination treatments targeting the BCR-signaling pathway. (A) Relative viability of L1236 (left) and L428 (right) cells exposed to ibrutinib subsequent to the indicated pretreatments (as in Figure 5G). Percentages reflect normalization to control (untreated [UT]; no pretreatment). Ibrutinib was administered at 2.5 nM for 24 hours. Data are presented as mean ± SD; *P < .05. (B) As in panel A, but exposed to idelalisib at 5 μM for 24 hours. (C) Immunoblot analysis to detect p-BTK/BTK and p-AKT/AKT levels in L1236 cells after single-agent or combination treatments or left UT as indicated; α-tubulin as a loading control (left). Relative densitometric values of the scanned immunoblot bands for the p-BTK/BTK (right, top) and p-AKT/AKT ratios (right, bottom), calculated after normalization to the corresponding α-tubulin signal intensities. (D) Heatmap-encoded effects of ibrutinib (left) and idelalisib (right) on the viability of the 8 cHL cell lines after the indicated pretreatments as in panels A and B (color coding for relative viability).