ADGRL4 and head and neck squamous cell carcinoma: Additionally, by profiling the ELTD1 expression in head and neck squamous cell carcinoma, a significant inverse correlation between CA9ELTD1 (a hypoxia–inducible gene) and ELTD1 mRNA levels was observed [80], probably because of a better perfusion in high ELTD1 tumors [18].