Figure 2. CircSPIDR inhibits cell growth and promotes apoptosis in CADC cells in vitro. (A, C) CCK-8 assays demonstrated that circSPIDR overexpression reduced HeLa cell viability (A), while circSPIDR inhibition with specific siRNAs (si-circSPIDR#1 or si-circSPIDR#2) increased HeLa cell viability (C). (B, D) Colony formation assays indicated that circSPIDR overexpression suppressed colony formation in HeLa cells (B), while circSPIDR inhibition promoted colony formation (D). (E, F) Representative images from flow cytometry analysis of apoptosis. Apoptotic cells were determined using Annexin V-FITC (X-axis) and PI (Y-axis) staining. CircSPIDR overexpression promoted HeLa cell apoptosis, while circSPIDR inhibition had the opposite effect. *P < 0.05; **P < 0.01; ***P < 0.001.