PTEN and neoplasm: Enhanced or aberrant activation of pathways like the PI3K/PTEN/AKT pathway [49,50,51] and WNT/β-catenin pathway [52,53] or constitutive STAT3 signaling [54] has been shown to play a role in NEN, especially NET, but has also been identified as an immune escape mechanism, leading to reduced cell infiltration within the tumor immune microenvironment [55,56].