In CAL27 cells, the growth of CYP1B1-WT tumours was much more rapid than that of p15 tumours, and the difference was significant 14 days post transplantation; the growth of CYP1B1-VAR tumours was even faster, but the difference between CYP1B1-WT and CYP1B1-VAR tumours remained below significance (Fig. 4a, left panel). Here, CYP1B1 is linked to neoplasm.