CD151 negatively regulates cytokine production in activated BMMCs by inhibiting ERK and PI3K pathway activation. BMMCs were unprimed or primed with IgE, then exposed to 100 ng/ml DNP-HSA for 24 h in the absence or presence of 10 μM LY294002 (LY), 100 nM Wortmannin (W), 10 μM PD98056 (PD) or DMSO vehicle control. NS, not stimulated controls. IL-4, IL-13, and TNF-α cytokine release by BMMCs was measured in culture supernatants by ELISA. Results shown are the mean ± SEM of three determinations. Filled columns indicate WT; open columns indicate CD151−/−. *p < 0.05.