BHLHE41 and head and neck squamous cell carcinoma: The hypoxic microenvironment in primary head and neck squamous cell carcinomas (HNSCC) and breast tumors induces the selection of a fraction of cells that concomitantly express hypoxia-related genes (GLUT1 and HIF-1α) and long-term dormancy genes, such as NR2F1, DEC2, and p27 [99].