STAT3 and neoplasm: In bone metastasis, TC-induced OCs secrete IL-19, a ligand of IL-20RB, initiating downstream JAK1/STAT3 signaling in TCs, thereby enhancing TC growth in bone.214 Concurrently, macrophages derived from Ly6C + CCR2+ inflammatory monocytes, characterized by elevated CD204 and IL4R expression, play a crucial role in the IL4R-dependent amplification of BC bone metastases.215 In a similar manner, the tumor-secreted protease cathepsin C regulates neutrophil recruitment and NETs formation, facilitating the degradation of microenvironmental heterogeneous signals, including platelet-reactive protein-1.