MAPK3 and lung carcinoma: For example, Wang et al. [45] observed significantly increased ERK1/2 activity after 24-h exposure to 0.5 μM MC-LR in murine epithelial ATII cells; however, Wang et al. [25] reported no significant changes in P-ERK1/2 following 24-h exposure to 1 μM MC-LR in human A549 lung cancer cells.