The results indicated that Ki67 positive staining showed brown‐yellow granules, and the number of Ki67‐positive expression cells and their degree of positive staining in tumor tissues were reduced in miR‐191‐5p‐A549‐injected mice, indicating that miR‐191‐5p treatment slows the proliferation of intratumoral cells to some extent (Figure 6e,f). The gene discussed is MKI67; the disease is neoplasm.