A. The expression of S100A9 and S100A8 protein in NOK, DOK and 7 oral cancer cell lines, respectively, detected by Western Blot analysis. Actin, a loading control. B. The staining of S100A9 protein in the tumor and stroma of two representative oral cancer specimens, respectively, with high and low stromal expression by IHC staining. Left panels, HE staining; Middle and Right panels, IHC staining of S100A9 and the enlargement of red box on the Middle panel (40X) highlighting the border between tumor and stroma in Right panel (200X). C. Kaplan-Meier analysis of recurrence-free survival for high and low stromal S100A9 groups. All the 79 patients were divided into two groups based on the mean expression of S100A9 in the tumor stroma. High, greater than mean. Low, equal to or less than mean.