For head and neck cancer per se, the scRNA-seq data from Puram study provide an ideal source for both training and validation purposes because the studied tumors have (1) uniformly varied tumor purity, and (2) it provides reference for subpopulations such as exhaustive CD8+ T cell that were not present in previous scRNA-seq experiments on melanoma and lung cancers. The gene discussed is CD8A; the disease is lung cancer.