TLR/MYD88 signaling promotes HCK expression in B-cell lymphoma cells. (A) HCK transcript levels by transcriptome analysis in MYD88-mutated bone marrow LPCs from WM patients (WM), peripheral CD19⁺ B cells (PB), and CD19⁺CD27⁺ memory B cells (MB) from healthy donors, and CD138⁺ bone marrow plasma cells (PC) from healthy donors. (B) Quantitative RT-PCR to detect HCK transcript levels was performed following stimulation with a TLR4 (LPS-EB), TLR9 (ODN-2006) for 24 hours in MYD88-mutated BCWM.1, MWCL-1, TMD-8, HBL-1 cells, and MYD88^WT OCI-Ly7, OCI-Ly19, and Ramos cells. (C) HCK protein expression was assessed by western blot analysis following stimulation with TLR4 (LPS-EB) and TLR9 (ODN-2006) agonists for 48 hours in MYD88-mutated BCWM.1 and MYD88^WT Ramos cells. (D) HCK protein expression by western blot analysis following transduction of vector only, or vectors expressing MYD88^WT or MYD88^L265P in BCWM.1 and Ramos cells. *P < .05; **P < .01; ***P < .001. endo-MYD88, endogenous MYD88; MYD88-flag, N-terminal flag-tagged MYD88; NS, not significant.