While differences were not statistically significant due to the likely heterogeneity of progressing versus regressing tumors, it is interesting to note that in contrast to the WT controls, none of the CB2-/- specimens had a high expression of the CD4+ T cell markers and genes involved in tumor regression (Figure 5A), suggesting a mechanism for CB2 contribution to tumor regression [16,56]. This evidence concerns the gene CD4 and neoplasm.