CCR4 and pituitary gland adenoma: Further studies have explored the specific mechanism by which macrophages affect the invasion ability of pituitary adenoma: on one hand, pituitary adenomas cause acidification of the TME, resulting in polarization of tumor‐related macrophages into an M2‐like phenotype (Figure 1, Procedure 3), whereas on the other hand, M2‐like macrophages secrete CCL17 and enhance the invasion ability of pituitary adenoma cells via the CCL17/CCR4/mammalian target of rapamycin complex 1 axis43 (Figure 1, Procedure 4).