A recent cGAS–STING prediction model defined biomarker genes that stratify tumors, including bladder cancer, lung adenocarcinoma, lung squamous cell carcinoma, skin cutaneous melanoma, and ovarian cancer, from the TCGA database into four distinct cGAS–STING groups (CSG 1–4) according to the clinical significance of cGAS–STING signaling in immunotherapy response. The gene discussed is CGAS; the disease is squamous cell lung carcinoma.