SELE and cancer: Importantly, naphthofluorescein did not further suppress the lung metastasis of B16F10 cells in Mint3 KO mice (Fig. 6e, f), indicating that the effect of naphthofluorescein on metastasis is attributable to host Mint3, which promotes metastatic niche formation in the lung by recruiting inflammatory monocytes and inducing the expression of E-selectin in endothelial cells that are adjacent to cancer cells in metastasis-affected lungs26.