Cai et al. (2006b) found conflicting results on a cellular level with stronger PEDF expression in HT115 colonic adenocarcinoma cell line and weaker expression in HRT-18 rectal adenocarcinoma cell line [11], however our results showed little difference in the expression of these two cell lines and therefore there may be other factors in these cell lines that may be responsible for the expression levels shown, such as such as tumour grading or stage. This evidence concerns the gene SERPINF1 and rectum adenocarcinoma.