MMP9 and neoplasm: The results obtained from real‐time PCR and Western blotting revealed that restoration of Let‐7i could reduce the mRNA and protein expression of oncogenic target genes including c‐Myc and MMP9, while its replacement led to the increment of both mRNA and protein expression of tumour suppressor genes including PTEN and KISS1 (Figures 3 and 4 *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).