The 3435CC genotype has usually been associated with higher levels of ABCB1 mRNA and protein and increased drug efflux in normal tissues and tumours (Hoffmeyer et al, 2000; Hitzl et al, 2001; Tanabe et al, 2001; Fellay et al, 2002; Vaclavikova et al, 2008), although some discrepancies have been reported, especially in Japanese populations (Nakamura et al, 2002). The gene discussed is ABCB1; the disease is neoplasm.