We thank Takatsugu Hirokawa, Seah Boon-Chieng, and Shigeki Mitaku for allowing us to use the SOSUI program for the prediction of transmembrane helical regions.

We are grateful to S. Minorikawa, E. Suzuki, S. Tsuda and N. Kashima for their excellent technical assistance. We also thank Dr. Takahiro Nagase and all our colleagues from the Kazusa cDNA project team for their cooperation. This study was supported by grants from the Kazusa Research Institute.