In order to further determine the role of SPHK1 in the regulation of POTEE-mediated oncogenesis, we firstly detected endogenous expression of SPHK1 in 11 colorectal cancer cell lines by qRT-PCR and western blot analysis to analyze the endogenous consistency between POTEE and SPHK1, and results showed that the endogenous expression level of SPHK1 was finely accordant with POTEE in quite a part of these cell lines, and we additionally chose HCT15 and HCT116 cells in our following experiments for their moderate expression of both POTEE and SPHK1 (Supplementary Fig. 4a, b). This evidence concerns the gene SPHK1 and colorectal cancer.