The expression level of Ki67, a cell proliferation marker, in the P. gingivalis group was significantly higher than that of the control group, indicating that the proliferation of tumor cells in the P. gingivalis group was more active and the degree of tumor malignancy was relatively high, which could be reversed by the decrease of SCD1 expression (Fig. 6d and Supplementary Fig. 8b). This evidence concerns the gene SCD and neoplasm.