Studies have shown that macrophages play an important regulatory role in promoting malignant tumour progression36, while LNMAT1 promotes lymphatic metastasis of BLCA through recruitment of CCl2-dependent macrophages37, and BMP4 induces polarization of M2 macrophages and facilitates tumour progression in BLCA38. The gene discussed is BMP4; the disease is bladder transitional cell carcinoma.