CYP1B1 and neoplasm: A number of studies failed to detect presence or activity of functional CYP1B1 protein in normal (nontumour) tissue (Murray et al, 1997; McFadyen et al, 1999); however, expression of CYP1B1 in normal tissue has been reported, although in much lower levels than in tumour tissue, at both mRNA and protein levels (Muskhelishvili et al, 2001; Gibson et al, 2003).