FGF2 and polycystic kidney disease: We previously fused the collagen-binding domain (CBD) and polycystic kidney disease (PKD) domain of Clostridium histolyticum class II collagenase (ColH) to bFGF and showed that the subcutaneous injection of this collagen-binding bFGF fusion protein (bFGF-PKD-CBD) without carrier into nude mice had more potent skin fibroblast growth-promoting effects at the injection site than native bFGF [17].