Map of transcription start sites in the human IL-12 p35 promoter. The first exon and 5′ flanking sequence (bases 1224-1703) are shown. Notations are made for the start site in lymphoblastoid cells (S2, −165), the cDNA start sites for NKSF (−126) and CLMF (−85), the TATA box (−32), the monocyte start site (S1, +1), and the two initiator methionine (Met) codons.