RGS5 and head and neck squamous cell carcinoma: To investigate fibroblast phenotypes present in HNSCC, we first broadly identified all fibroblasts based on lumican expression (LUM+; 4,894 cells); fibroblasts clustered closely with RGS5 + mural cells (2,174 cells), which included pericytes and smooth muscle cells (SMCs; Supplementary Fig. 3A, B).