To prove clustering of β1 integrin in ceramide-enriched membrane platforms in vivo, we labeled B16F10 tumor cells with CFSE, injected the cells into wild-type or acid sphingomyelinase-deficient mice, took blood 5 min after injection, performed a Ficoll gradient to remove erythrocytes and to purify tumor cells, fixed the cells, and stained with Cy3-anti-ceramide and Cy5-anti-β1 integrin. Here, SMPD1 is linked to neoplasm.