We further confirmed the activity of SPA70 in blocking the agonist-induced transcriptional activity of hPXR, and we demonstrated that SPA70 was able to block rifampicin induction of MDR1, another hPXR transcriptional target, in the human colorectal adenocarcinoma cell lines LS180 and LS174T (Fig. 2b and Supplementary Fig. 2). The gene discussed is ABCB1; the disease is colorectal adenocarcinoma.