Arresten, a cleaved fragment of type IV collagen α1 chain, is expressed in normal rat cardiac tissue. However, its function on the cardiac fibroblasts has not been fully elucidated. This study investigated the effects of arresten on migration and proliferation of cardiac fibroblasts and underlying mechanisms. Cardiac fibroblasts were isolated from ventricles of adult Wistar rats. Cell migration and proliferation were measured by Boyden chamber assay and cell counting assay, respectively. Phosphorylation of extracellular signal-regulated kinase (ERK) and Akt (Ser473) was evaluated by Western blotting. Arresten significantly promoted the migration (250 ng/ml, 24 h) and proliferation (100 ng/ml, 48 h) in cardiac fibroblasts. Arresten (30 min) enhanced phosphorylation of ERK (250 ng/ml) and Akt (Ser473) (100 ng/ml). The arresten (250 ng/ml, 24 h)-induced migration was suppressed by PD98059 (10 μM), an inhibitor of MEK/ERK. The arresten (100 ng/ml, 48 h)-induced proliferation was suppressed by LY294002 (1 μM), an inhibitor of PI3K/Akt. This study for the first time demonstrated that arresten promotes the migration via MEK/ERK signaling pathway, while it promotes the proliferation via PI3K/Akt signaling pathway.