We report that the CYP genes with highest expression, ranked by the mean expression in tumor tissues for all patients, are: CYP1B1 (mean normalized expression 112.8), CYP4Z1 (92.2), CYP2A6 (75.7), CYP4X1 (65.1), CYP4B1 (31.5), CYP2A7 (30.8), and CYP4F8 (11.6). The gene discussed is CYP4Z1; the disease is neoplasm.