CD274 and lung cancer: To explore whether PIK-93–mediated reduction of PD-L1 protein expression results from cytotoxicity, we investigated PIK-93–mediated cell survival in CL83, HOP92, H522, H1975, PC9, and A549 lung cancer cell lines and the HFB normal fibroblast cell line by the sulforhodamine B (SRB) assay.