SIX1 and pachyonychia congenita: Thus, these findings are in accordance with our previous report that Cyclin D1 is a downstream regulator of the USP1-SIX1 axis responsible for the phase transition from the G0/G1 to S phase, demonstrating that Cyclin D1-driven cell cycle progression is a critical target for the SIX1 degradation inducer against castration resistance of PC.