HA14-1 is a Bcl-2 inhibitor that is widely used for studies of apoptosis. In the course of searching for a ceramide glucosyltransferase inhibitor that catalyzes the first glycosylation step of glycosphingolipid synthesis, we unexpectedly found that HA-14-1 also has the ability to inhibit ceramide glucosyltransferase. The IC50 value of HA14-1 against ceramide glucosyltransferase is 4.5 mu M, which is lower than that reported for Bcl-2 in vitro. Kinetic analyses revealed that HA14-1 is a competitive and mixed-type inhibitor with respect to C-6-NBD-ceramide and UDP-glucose, respectively. (C) 2013 Elsevier Inc. All rights reserved.