CYBB and metastatic neoplasm: While details regarding the contribution by NOX2-derived ROS for the induction and progression of cancer remain to be elucidated, it seems likely that the impact of NOX2 is confined mainly to primary and metastatic tumors that are infiltrated by immunosuppressive NOX2+ myeloid cells and to myeloid leukemias, where the malignant clone comprises NOX2+ cells.