Representative photomicrographs of CD31-positive cells and Ki67-positive cells in the tumor are shown in Figure 2A. The microvessel density in the stress+chewing group was significantly lower than that in the stress group (p < 0.01, Figure 2B), and the protein expression of CD31 in the stress+chewing group was significantly lower than that in the stress group (p < 0.01, Figure 2D), indicating that chewing behavior during psychological stress remarkably attenuated the increased tumor vascularity. Here, PECAM1 is linked to neoplasm.