USP17 expression was negatively associated with glioma tumor grade, but increased in both SqCC and ADC patient tissues and correlated with recurrence and metastasis.76, 77, 78 A pro-tumorigenic mechanism of USP17 is to stabilize a key regulator of cellular division, phosphatase cdc25 (ref. 79) and a key EMT transcription factor, Snail1,80, 81 both of which are crucial for breast cancer progression and metastasis. This evidence concerns the gene SNAI1 and central nervous system cancer.