A drug for promoting ceramide transport contains a protein having the amino acid sequence of SEQ ID NO:1 as an effective component; the base sequence of SEQ ID NO:3; a method of measuring an activity for promoting ceramide release comprises mixing a lipid membrane containing ceramide with a drug promoting ceramide release, centrifuging the thus obtained mixture to give a supernatant and measuring the ceramide content in the supernatant; and a method of measuring an activity for promoting intermembrane ceramide transfer comprises mixing a receiving membrane, a drug for promoting ceramide transport and a donating membrane containing ceramide, adding a selective membrane aggregating agent thereto, then separating the receiving membrane from the donating membrane and measuring ceramide contents in the receiving membrane and in the donating membrane. Thus, it is possible to provide a drug for promoting ceramide transport, a base sequence for producing the drug, relevant a method of measuring an activity for promoting ceramide release and a method of measuring an activity for promoting intermembrane ceramide transfer.