MAPK3 and cancer: In contrast, moderate amplitude 24-h EF stimulation of the cancer cells (U87-GBM) increased the phospho-p38 MAPK protein expression (at 12, 24, and 36 h), and a slight increase in the p38 protein expression at 24 h, while again, no detectable changes in the protein expression of p44/42 ERK1/2 and AKT pathways are observed (Figure 5, bottom right panel).