Recently, Felger et al. (2011) investigated in vivo p38 MAPK response in peripheral blood lymphocytes to the initial injection of IFN-α in eleven patients with HCV: increase in the percentage of lymphocytes positive for phosphorylated p38 was significantly greater in patients who developed clinically significant symptoms of depression during the first 12 weeks of IFN-α treatment [38]. The gene discussed is MAPK14; the disease is major depressive disorder.