HRAS and neoplasm: Based on these results, we elucidated for the first time the specific mechanism by which RGD-p21Ras-scFv exerts its antitumor activity: RGD-p21Ras-scFv enters tumor cells and binds to p21Ras, reduces the expression of active p21Ras (p21Ras-GTP) protein, and further inhibits the phosphorylation of MEK-ERK/PI3K-AKT signaling pathway.