- CKAP4/p63 Is a Receptor for the Frizzled-8 Protein-related Antiproliferative Factor from Interstitial Cystitis Patients. Conrads, T.P., Tocci, G.M., Hood, B.L., Zhang, C.O., Guo, L., Koch, K.R., Michejda, C.J., Veenstra, T.D., Keay, S.K. J. Biol. Chem. (2006)