SAMHD1 and urinary bladder cancer: NR1H3 is a nuclear receptor component and an anti-invasive gene for bladder cancer [23]; PARP12 has been reported to suppress hepatocellular carcinoma metastasis [24]; SAMHD1 is yet another suppressor of epithelial transformation [25]; PSMB9 is a key metastasis suppressor for breast cancer [26].