**Acknowledgment**

We thank Dr. Y. Yodoi for generously providing YT-Al cells, and Ms. Tamayo Hatayama, Satomi Hatada, Yoshiko Yamashita, Minako Kato, Tomoko Sueishi, Keiko Kimura, Misao Kuroki, Naomi Miyahara, and Shoko Yamamoto for their technical help. This study was supported by Special Coordination Funds for Promoting Science and Technology (H18-1-3- 3-1), JSPS KAKENHI Grants (19790431, 18390186, 19659153, 19790411, 20890270, 20390178 and 22700933), The Takeda Science Foundation (Tokutei Kenkyu Josei I, 2008), Kawasaki Medical School Project Grants (18-209T, 19-407M, 19-603T, 19-205Y, 19-506, and 20-210O), and The Kawasaki Foundation for Medical Science and Medical Welfare (KYOIKU KENKYU JOSEI-2).
