To determine the pathway responsible for activating MEF2C during lymphoid lineage specification, lineage negative (lin-) cells were treated with small molecule inhibitors targeting either p38 MAPK (SB203580, PubChem176155, or p38i) or ERK5 (U0216, PubChem3006531, or ERKi) (Fig 5A without viral infection). This evidence concerns the gene MAPK7 and viral infectious disease.