SYK activation is driven by the SFK HCK in MYD88 mutated lymphoma cells. (A) Relative p-HCK^Tyr410 levels by PhosFlow analysis following the treatment with dimethyl sulfoxide (DMSO) or the HCK inhibitor A419259 at the indicated concentrations for 1.0 hour in vector-only, HCK^WT, or HCK^Thr333Met transduced BCWM.1 cells. (B) Relative p-SYK^Y525/526 levels by PhosFlow analysis following treatment with DMSO or A419259 at indicated concentrations for 1.0 hour in vector-only, HCK^WT, or HCK^Thr333Met transduced BCWM.1 cells. (C) Relative p-HCK^Tyr410 levels by PhosFlow analysis following the treatment with DMSO or A419259 at indicated concentrations for 1.0 hour in vector-only, HCK^WT, or HCK^Thr333Met transduced MWCL-1 cells. (D) Changes in p-SYK^{Tyr525/Tyr526} levels following the treatment with DMSO or A419259 at indicated concentrations for 1.0 hour in vector only, HCK^WT, or HCK^Thr333Met transduced MWCL-1 cells. The expression levels of total SYK in these cells as well as protein loading control GAPDH are also shown. (E) Relative p-HCK^Tyr410 levels by PhosFlow analysis following the treatment with DMSO or A419259 at indicated concentrations for 1.0 hour in vector only, HCK^WT, or HCK^Thr333Met transduced TMD8 cells. (F) Changes in p-SYK^{Tyr525/Tyr526} levels following the treatment with DMSO or A419259 at indicated concentrations for 1.0 hour in vector-only, HCK^WT, or HCK^Thr333Met transduced TMD8 cells. The expression levels of total SYK in these cells as well as protein loading control GAPDH are also shown. (G) p-HCK^Tyr410 levels and p-SYK^{Tyr525/Tyr526} levels by PhosFlow analysis following the treatment with DMSO or A419259 at the indicated concentrations for 1.0 hour in CD20⁺ gated patient with WM bone marrow lymphoplasmacytic cells. Above experiments were performed at least twice with representative results shown. Ab, antibody.