SLC6A4 and adenoma: No significant differences in serotonin transporter (SERT), apical sodium bile acid transporter (ASBT), cystic fibrosis transmembrane conductance regulator (CFTR), downregulated-in-adenoma (DRA), monocarboxylate transporter 1 (MCT-1), Niemann-Pick C1-like protein 1 (NPC1L1), sodium-hydrogen exchanger 3 (NHE3), or sodium-coupled monocarboxylate transporter (SMCT-1) expression were observed between GF and SPF mice (Supplementary Fig. S2).