CES1 and head and neck squamous cell carcinoma: Subsequent validation of CES1 expression at RNA and protein levels between HNSCC-PDO and HNSCC-PDOcis-R using RT-PCR and WB revealed that the expression level of CES1 in HNSCC-PDOcis-R was 17.697 times higher than in the PDO (Figs. 6I and 6J).