5-ALA-PDT induces PCD in cancer cells through the generation of ROS.5 To determine whether MEK inhibition increases ROS generation after 5-ALA-PDT, we monitored the conversion of DCFH-DA to DCF in DLD-1 cells treated with control vehicle, U0126, 5-ALA-PDT or U0126/5-ALA-PDT (Fig. 4a). The gene discussed is MAP2K7; the disease is cancer.