Purpose.To understand the biological activity of entactin, a component of the basement membrane of the corneal epithelium, we investigated the ability of rabbit corneal epithelial cells to attach to an entactin matrix and the effect of entactin on the cells' attachment to other corneal basement proteins.Methods.Multiwell plastic plates were coated with bovine serum albumin (BSA), alone or with BSA and entactin, laminin, fibronectin or collagen type IV. Cultured rabbit corneal epithelial cells were seeded on the plates. After incubation (usually 90 min), the cells were fixed and stained with 1% crystal violet. The number of attached cells was counted under a light microscope.Results.The numbers of attached cells increased in proportion to both the incubation period and the concentration of entactin coated. Furthermore, the number of cells attached to the entactin-coated plate was greater than the number attached to the BSA-coated plate for each incubation period (30 to 120 min). Likewise, when laminin-coated plates were treated with entactin, the number of the attached cells increased in proportion to the concentration of entactin. However, entactin did not affect the cellular attachment to fibronectin or type IV collagen. Cellular attachment to entactin was partially inhibited by the cells' preincubation with the synthetic peptide (GRGDSP).Conclusions.The present results showed that cultured corneal epithelial cells adhere to entactin and that entactin stimulated the attachment of these cells to the laminin matrix. These findings suggest that entactin plays a specific role in maintaining the normal integrity of the corneal epithelium.