MAPK8 and acute myeloid leukemia: Therefore, we determined whether Akt and MAPK activation was affected by penfluridol treatment of AML cells, and found that penfluridol suppressed activation of Akt, JNK, and ERK1/2, but induced p38 MAPK activation at different time points in U937 and HL-60 cells (Fig. 3a).