GPNMB and neoplasm: To better understand these tumor immune differences, the authors of the article explored the subtypes and functions of the tumor macrophages, and they identified five macrophage subclusters distributed as follows: C1Q+ macrophages were mainly enriched in TPIT lineage tumors and mainly function in prompting protein synthesis and hormone secretion pathways; GPNMB+ macrophages were enriched in PIT1 lineage tumors and function in phosphorylation and metabolism pathways, and CX3CR1+ macrophages were enriched in SF1 lineage tumors which help in controlling tumor growth.