Bestatin (Ubenimex) competitively inhibits many aminopeptidases, including B, N and leucine aminopeptidases. Ubenimex is a microbial metabolite and dipeptide with potential immunomodulatory and antitumor activities. Aminopeptidases has been implicated in the process of cell adhesion and invasion of tumor cells. Therefore, inhibiting aminopeptidases may partially attribute to the antitumor effect of ubenimex. This agent also activates T lymphocyte, macrophage, and bone marrow stem cell as well as stimulates the release of interleukin-1 and -2, thus further enhances its antitumor activity.

在B16-BL6黑色素瘤细胞荷瘤的小鼠背部侧中,Bestatin使既定原发性肿瘤块血管的数量下降.在小鼠背部气囊测定中,Bestatin显著抑制黑色素瘤细胞诱导的血管生成. 在EGDA大鼠中,Bestatin可降低EAC的发病率（57.7％降至26.1％）.在EGDA大鼠的食管组织中,Bestatin对白三烯B4生物合成的抑制具有明显的统计学意义.

Bestatin对SN12M细胞侵入重组基底膜（基质胶）具有浓度依赖性的抑制作用。在非肿瘤条件培养基中,其还可浓度依赖性抑制肿瘤细胞IV型胶原退化。在U937细胞中,乌苯美司可使caspase-3的活性增强并诱导DNA梯和DNA片段化。在SN12M Bestatin抑制氨基肽酶底物的水解活性。Bestatin对人脐静脉内皮细胞中的管状形成具有抑制作用。通过固定在细胞表面的亮氨酸氨肽酶,Bestatin直接刺激淋巴细胞（和单核细胞）,而间接刺激则是通过氨基肽酶乙抑制吞噬作用激素的分解代谢发挥。

Cells are harvested, washed, and lysed in NP-40 lysis buffer (50 mM Tris-HCl [pH 7.5], 150 mM NaCl, 0.5% NP-40). Total cell protein is quantified using the Bradford assay and 1-mg/mL protein aliquots are made. Ten microliters of total cell protein is mixed with 290 μL of substrate solution (0.1 mg/mL dithiothreitol [DTT], 0.1 mg/mL albumin, and 1 mM alanine-β-naphthylamide). Fluorometric measurements (340 nm excitation, 400 nm emission) are made after 15 and 30 min. The slope of the line between the 15- and 30-min measurements is used to represent aminopeptidase activity. Total cell protein is preincubated with bestatin, amastatin, puromycin, EDTA, and/or ZnCl2 for 20 min before the fluorometric aminopeptidase assay.

Growing cells (1×106 to 2×106 cells/mL) are diluted to 1.0×103 cells/mL and transferred (3 mL) into a well in a 12-well multiwell plate (2.5-cm diameter/well). Cells are treated with 0, 10, 50, 100, 300, or 600 μM Bestatin and allowed to grow at 21°C shaking at 180 rpm for 48 h. A hemocytometer is used to measure cell density after 0, 24, and 48 h.