MAPK3 and lung carcinoma: The retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN), a cell proliferation inhibitor and apoptosis inducer has been shown to induce Egr-1 expression through ERK1/2 signaling pathway rather than activation of p38 in lung cancer cells [32].