HOXB9 and cancer: We introduced the HOXB9 construct into the HT29 and HCT116 cancer cell lines (HT29-T and HCT116-T, respectively), both of which showed low HOXB9 mRNA expression relative to that in the other human colorectal cancer cell lines (Additional file 1: Figure S1c), in order to evaluate the functional consequence of HOXB9 overexpression in colorectal cancer.