MAPK3 and lung cancer: Several studies have demonstrated the importance ofERK and its regulated genes in PPARγ agonist-induced apoptosis [14–16, 41].In human lung cancer cells, troglitazone induced apoptosis as well as PPARγ and ERK1/2 accumulation in the nucleus.Both PPARγ siRNA and U0126, a specific inhibitorof ERK1/2, blocked these effects of troglitazone, suggesting thattroglitazone-induced apoptosis is PPARγ- and ERK1/2-dependent.