CYCS and thyroid cancer: The effect of FOXD2-AS1 on the expression of cytochrome C (CytoC) and the caspase-3 and -9 activity were further examined, and we found that silencing FOXD2-AS1 enhanced the expression of CytoC and the activity of caspase-3 or -9 in thyroid cancer cells (Figures 4C–E).