C5 and neoplasm: In this study, PPIP5K2 knockdown reduced tumor volume and weight, whereas intraperitoneally injected protein C5 (0.025 mg/kg, every second day) in PPIP5K2-depletion tumor led to an increase of tumor size as compared with the normal saline (NS) control, demonstrating that C5 promotes tumor progression as a downstream target of PPIP5K2 (Fig. S5D-F).