To explore the upstream molecular mechanisms that modulate COMMD6 expression in human cancer, we constructed a potential competing endogenous RNA (ceRNA) network, which has been reported to be a new and complex regulatory network involved in many diseases including cancer.24 Firstly, 17 upstream microRNAs (miRNAs) of COMMD6 were predicted using miRanda, miRDB, miRwalk and Targetscan databases, such as has-miR-561 and has-miR-340 (Fig. 4a). The gene discussed is COMMD6; the disease is cancer.