CD4 and neoplasm: The physical nature of tumor angiogenesis, characterized by lack of pericyte coverage of vessels, tortuous vessel path and leakiness, may exclude T cells from approaching the tumor.153 The genetic deletion of RGS5 in mice not only restores pericyte maturation and results in vessel normalization, but also improves CD8+ and CD4+ T cell trafficking after adoptive transfer to tumor parenchyma in RIP1-Tag5 mouse tumor model.154 This correlated with improved survival of tumor-bearing mice.154