We found that Rap1a−/−, Rap1a siRNA transfected and GGTI-2147 treated myeloid cells failed to accumulate in the tumor microenvironment (Figure 5E), indicating that Rap1a, like p110γ and integrin α4β1 (9–10), is required for myeloid cell trafficking to tumors. The gene discussed is RAP1A; the disease is neoplasm.