Integrin-mediated adhesion to the extracellular matrix plays a fundamental role in tumor metastasis. Salvicine, a novel diterpenoid quinone compound identified as a nonintercalative topoisomerase II poison, possesses a broad range of antitumor and antimetastatic activity. Here, the mechanism underlying the antimetastatic capacity of salvicine was investigated by exploring the effect of salvicine on integrin-mediated cell adhesion. Salvicine inhibited the adhesion of human breast cancer MDA-MB-435 cells to fibronectin and collagen without affecting nonspecific adhesion to poly-L-lysine. The fibronectin-dependent formation of focal adhesions and actin stress fibers was also inhibited by salvicine, leading to a rounded cell morphology. Furthermore, salvicine down-regulated B1 integrin ligand affinity, clustering and signaling via dephosphorylation of focal adhesion kinase and paxillin. Conversely, salvicine induced extracellular signal-regulated kinase (ERK) and p38 mitogenactivated protein kinase (MAPK) phosphorylation. The effect of salvicine on B1 integrin function and cell adhesion was reversed by U0126 and SB203580, inhibitors of MAPK/ERK kinase 1/2 and p38 MAPK, respectively. Salvicine also induced the production of reactive oxygen species (ROS) that was reversed by ROS scavenger N-acetyl-L-cysteine. N-acetyl-L-cysteine additionally reversed the salvicine-induced activation of ERK and p38 MAPK, thereby maintaining functional B1 integrin activity and restoring cell adhesion and spreading. Together, this study reveals that salvicine activates ERK and p38 MAPK by triggering the generation of ROS, which in turn inhibits B1 integrin ligand affinity. These findings contribute to a better understanding of the antimetastatic activity of salvicine and shed new light on the complexroles of ROS and downstream signaling molecules, particularly p38 MAPK, in the regulation of integrin function and cell adhesion.