Provided are non-naturally occurring cystine knot peptides (CKPs) that bind to VEGF-A. Additionally, provided are methods of using non-naturally occurring CKPs that bind to VEGF-A, including diagnostic and therapeutic compositions and methods. Non-naturally CKPs that bind low density lipoprotein receptor-related protein 6 (LRP6) are also provided.本發明提供可結合VEGF-A之非天然存在之胱胺酸結肽(CKP)。另外,提供使用可結合VEGF-A之非天然存在之CKP的方法,包括診斷性及治療性組合物及方法。亦提供可結合低密度脂蛋白受體相關蛋白6(LRP6)之非天然CKP。