CYP19A1 and head and neck cancer: Negatively regulated by ERβ1; overexpressed in aromatase inhibitor resistant estrogen receptor-positive (ER+) breast cancer; upregulated after genistein treatment; associated with cycling hypoxia; inversely correlated to metastasis in lung adenocarcinoma; upregulated in head and neck cancer cell lines; downregulated in chronic myelogenous leukemia stem cells; upregulated in T-cell prolymphocytic leukemia