ANGPTL1 and head and neck squamous cell carcinoma: HNSCC samples from the HPA database showed absent ANGPTL1 protein expression (staining intensity score = 1), while normal oral mucosa maintained moderate expression (score = 2) (Supplementary Figure 3A), and expression was further reduced in patients with TNM stage II-III (stage I/II vs stage III/IV: log2FC = 0.47, p = 0.0038) (Supplementary Figure 3B).