A non-human animal which has a reduced amount of functional TAZ polypeptide and/or TAZ-like polypeptide, or a reduced amount of nucleic acid encoding said polypeptide. A method for generating a non-human animal which develops PKD comprising reducing the amount of functional TAZ polypeptide and/or TAZ-like polypeptide, or nucleic acid encoding said polypeptide. A method of screening for compounds of use in preventing or treating PKD wherein a non-human animal is administered with a test compound and the effect of the test compound on the amount or function of TAZ polypeptide and/or a TAZ-like polypeptide and/or a polypeptide regulated by TAZ or a TAZ-like polypeptide function, or the amount of nucleic acid encoding said polypeptide, is assessed.