At least some of these genes have been shown to vary in expression in colorectal tumours, including GST-M1, ALDH and lysozyme (Yuen et al, 1998; Saadat and Saadat, 2001), and could play a functional role in the cellular response to camptothecin and its derivatives. The gene discussed is GSTM1; the disease is colorectal neoplasm.