To address whether IL-10 production by Th2 and Th17 cells was also dependent on ERK1 and ERK2 activation, we differentiated these cells with anti-CD3 and anti-CD28 in the absence of APCs (Shoemaker et al., 2006; Veldhoen et al., 2009; Veldhoen et al., 2006), in the presence or absence of the MEK inhibitor (PD184352).