Results of CCK-8 also showed that compared with the NC miRNA + empty vector group, hsa-miR-557 could inhibit the proliferation of osteosarcoma cells at 48 h (p = 0.0003, q = 6.522) and 72 h (p < 0.0001, q = 13.84), KRAS could promote the proliferation of osteosarcoma cells (48h: p < 0.0001, q = 8.080; 72 h: p < 0.0001, q = 12.380), while the transfection of hsa-miR-557 could inhibit the effect of KRAS (NC miRNA + KRAS vector vs hsa-miR-557 + KRAS vector, 48 h: p < 0.0001, q = 7.815; 72 h: p < 0.0001, q = 14.72) (Figure 5C). This evidence concerns the gene KRAS and osteosarcoma.