While the precision of the histological scoring system63,64 used to quantify colitis severity by accounting for combined immune infiltration, ulceration, and crypt remodeling may be insufficient to identify significant gefitinib- or EGF-induced changes (Figs 1f, 2e and 3e,l), differences in proinflammatory cytokine expression may underlie downstream changes in crypt loss or mucosal healing (as depicted in Figs 1e, 2d and 3f,g,m,n). The gene discussed is EGF; the disease is colitis.