SHH and infection: To delineate the requirement of Smurfs for Shh-induced Ptch1 turnover, we tookthe advantage of the conditionalSmurf1−/−;Smurf2fl/flMEFs, and quantified the turnover rate of exogenously expressed Ptch1-FLAGfollowing cyclohexamide treatment without or with removal of theSmurf2 alleles following Ad-cre infection.