Effect of miR-155 overexpression on SHIP1 protein expression and AKT and ERK activation in NK cells. (A) NK1.1⁺CD3⁻ NK cells from wt and miR-155 tg mice were analyzed for SHIP1 protein levels by immunoblot. Actin was assessed to ensure equal loading. (B) NK1.1⁺CD3⁻ NK cells from wt and miR-155 tg mice were left untreated or stimulated with IL-2 (90 ng/mL) or IL-15 (100 ng/mL) for 10 minutes. Immunoblot analysis was performed on total lysates using anti-phospho-ERK^{Thr202/Tyr204}, anti-phospho-AKT^Ser473, and actin Abs. (C) NK1.1⁺CD3⁻ NK cells from wt and miR-155 tg mice and paraformaldehyde-treated YAC-1 cells were mixed and incubated at a ratio of 5:1 for the indicated times. Lysates from NK-cell and YAC-1 samples were analyzed by immunoblot using anti-phospho-ERK^{Thr202/Tyr204} and actin Abs. These blots are representative of at least 2 independent experiments.