Expression of a catalytically inactive mutant of p38 MAPK blocks the DP-to-SP differentiation of Thy278/107 cells.

(A) Cell lysates from Thy278/107 cells transfected with empty vector (mock; M) and 3 independent lines established after transfection of a catalytically inactive mutant of human p38β MAPK (dnp38) were immunoblotted with a polyclonal antibody to p38 MAPK to test for protein abundance. (B) Thy278/107 cells (wild-type) or a line expressing a kinase-dead mutant of p38 MAPK (dnp38.7) were cultured alone (dotted line) or with SEA-pulsed APCs (solid line). After 3 days, cultures were analyzed for the expression of the indicated surface markers by flow cytometry.