PIK3CA and neoplasm: It is also important to consider that PI3K-α and β isoforms are predominantly expressed in non-immune cells; on the contrary, PI3K-Υ or δ isoforms largely control PI3K pathway activation in immune cells (T-cells, myeloid derived suppressor cells, and T-regs); because of these findings, the use of agents specifically directed to PI3K α and β isoforms, which are mainly detected in the tumor cells, can produce only marginal side effects on TILs and other immune cells in the tumor microenvironment [95,104].