ID1 and cancer: Moreover, overexpression of an alternatively spliced isoform of the inhibitor of differentiation-1 (Id-1B) in PC3 PCa cells maintains cell quiescence, self-renewal, and cancer stem cell-like properties with increasing the proportion of cells in the G0–G1 phase of the cell cycle with high p27 levels and reduced p-Erk and cyclin A levels [44, 45].