IL34 and neoplasm: When visualizing the expression of ligands and receptors in the CSF/IL34/CSF1R signaling axis, it was noted that in normal tissues, MFAP5+ fibroblasts predominantly secreted CSF-1, which is recognized as a classic tumor-promoting factor that recruits macrophages to tumor sites and facilitates the polarization of TAMs (118), to interact with C1QC+ macrophages; however, in tumors, MFAP5+ fibroblasts exclusively released IL-34, another cytokine capable of binding to CSF1R on C1QC+ macrophages.