MG-262[Z-Leu-Leu-Leu-B(OH)2]，一种硼酸肽，是一种有效的蛋白酶体抑制剂，选择性地和可逆地抑制蛋白酶体的胰凝乳蛋白酶活性。MG-262由多肽和硼酸部分组成，起着抑制蛋白酶体的作用。据报道，MG-262能够减少鼻粘膜和息肉成纤维细胞的细胞活力，诱导细胞生长停滞，抑制DNA复制和视网膜母细胞瘤磷酸化，增加细胞周期抑制子p21和p27的表达，通过线粒体膜电位损耗，caspase-3和聚（ADP-核糖）聚合酶的激活，诱导c-Jun的磷酸化和丝裂原活化蛋白激酶磷酸酶-1（MKP-1）的表达从而诱导细胞死亡。

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