CXCR4 and neoplasm: According to Liang et al. [28], synthesized precursor miRNA can significantly reduce the expression of CXCR4, thus reducing the CXCR4/SDF-1 pathway-mediated tumour invasion and metastasis, suggesting that miRNA can be used as an upstream factor of CXCR4 pathway in the regulation of tumour metastasis.