CDKN1A and neoplasm: To examine how ZEB1 enhances UM cell division thereby tumor growth we checked the expression levels of cell cycling-related genes and found that all detected CDKIs, except for CDKN2B (P15INK4B), including CDKN1A (P21CIP1), CDKN1B (P27KIP1), CDKN2A (P16INK4A/P14ARF), CDKN2C (P18INK4C), and CDKN2D (P19INK4D) together with the nuclear phosphoprotein RB1 were underexpressed in UM and MetUM compared to NUM (Fig. 6A‒H).