priority journal Animals article mouse controlled study nonhuman Humans Mice animal cell human mitogen activated protein kinase p38 protein expression signal transduction NIH 3T3 Cells animal cell proliferation human cell metabolism p38 Mitogen-Activated Protein Kinases unclassified drug Apoptosis Enzyme Inhibitors Gene expression Phosphorylation Proteins RNA, Messenger Signal Transduction cell survival enzyme activity enzyme inhibition