SHB and neoplasm: Our recent finding that CD8+ cell infiltration into B16F10 melanomas was influenced by the Shb gene raised the possibility that endothelial cells exert an influence on immune responses to tumors in a manner that could be of relevance to tumor expansion and metastasis4, and we decided to investigate this further by crossing the Cdh5-CreERT2(1Rha) transgene Cre-recombinase onto the Shbflox/flox background.