TGFB1 and head and neck squamous cell carcinoma: In HNSCC tissue, TGF‐β1 was produced by several types of the cells (Figure S2A) and its receptor, TGFBR2 as well as POSTN was preferentially expressed in tumors including where p‐EMT program was detected (MEEI5, 16, 17, and 28) (Figure S2B).