MAPK3 and lung adenocarcinoma: To detect the adequate amount level of PRKAR1A expression required for the upregulation of the extracellular signal kinase (ERK)1/2, which is frequently involved in the regulation of lung adenocarcinoma cell proliferation and migration23, 24, we tested the phosphorylation level of ERK1/2 in PRKAR1A knockdown or upregulated cells by WB.