DLK1 and cancer: We suggest that the DLK1/RAC1-induced increase in ROS is the cause of chromosomal instability,2 which in turn leads to more undifferentiated tumors.51 Interestingly, RAC1 activation was shown to drive proliferation of intestinal stem cells52 and targeting RAC1 suppresses cancer cell viability,53 cancer stem cell activities,54 and metastasis.55 Wang et al.56 reported that RAC GTPase-activating protein 1 is associated with early recurrence in HCC.