IL-6 but not IL-6R transcription is induced by mutated MYD88. Expression of IL-6 (A) and IL-6R (B) transcripts using TaqMan Gene Expression Assays in MYD88-mutated and MYD88 WT cell lines. The number of healthy donors that were evaluated for nonmemory (open circles) and memory (open triangles) B cells, as well as the number of WM patients that were evaluated for LPC (open diamonds) are shown. IL-6 (C) and IL-6R (D) transcript levels were also determined by TaqMan Gene Expression Assays in primary LPCs (CD19⁺) from MYD88 L265P expressing WM patients, and HD-derived nonmemory (CD19⁺CD27⁻) and memory (CD19⁺CD27⁺) B cells. P < .01 for comparison of IL-6 or IL-6R transcript levels in WM LPC vs either HD nonmemory or memory B cells. IL-6 (E) and IL-6R (F) transcription following over-expression of MYD88 L265P or WT protein in cell lines expressing mutated or WT MYD88. Total Flag-tagged MYD88 L265P or WT protein, as well as GAPDH protein levels determined by immunoblotting are shown for all transduced cell lines in Figure 1C.