Moreover, rhein extracted from Rheum palmatum L. attenuated Rac1 and therefore inhibited migration and invasiveness of ovarian cancer (SKOV-3-PM4) cells through matrix metalloproteinases (MMPs) and Rac1/ROS/MAPK/AP-1 (Rac1/reactive oxygen species/mitogen-activated protein kinase/activating protein-1) pathway. The gene discussed is RAC1; the disease is ovarian cancer.