tokens: Three binding sites for C/EBP proteins are found in the human immunodeficiency virus type 1 ( HIV-1 ) long terminal repeat ( LTR ) ( V.M. Tesmer , A.Rajadhyaksha , J.Babin , and M.Bina , Proc.Natl.Acad.Sci. USA 90 : 7298-7302 , 1993 ) .