CXCL12 and colorectal carcinoma: Among the dominant bacteria in stage I-II CRC group, g__Lachnospiracea_incertae_sedis.s__uncultured_bacterium_adhufec37.25 had observable positive correlation with multiple checkpoints (TNFSF18, BTNL2 and VTCN1 etc.)(see Additional file 1: Fig. S1), immune-activating genes (TNFRSF17, ENTPD1 and CXCL12 etc.)(Fig. 5A), immunosuppressive genes (LAG3, KDR and IL10, etc.)(as in Additional file 2: Fig. S2), chemokines (CXCL6, CCL8 and CCL14 etc.)(as in Fig. 5C) and chemokine receptors (CCR2) (as in Additional file 3: Fig. S3).