IL-21 enhances and sustains CD8+ T cell responses to achieve durable tumor immunity: comparative evaluation of IL-2, IL-15, and IL-21.

Moroz A, Eppolito C, Li Q, Tao J, Clegg CH, Shrikant PA. "IL-21 enhances and sustains CD8+ T cell responses to achieve durable tumor immunity: comparative evaluation of IL-2, IL-15, and IL-21." J. Immunol.. 2004;173(2):900-9.