Therefore, we firstly investigated the possibility of ifosfamide turnover in human breast cancer microsomes using highly sensitive HPLC/UV and LC/MS detection methods to determine ifosfamide metabolites and Western Blotting to detect the expression of CYP3A4, CYP2C9 and CYP2B6 proteins in the tumours. The gene discussed is CYP2B6; the disease is breast carcinoma.