Functional analysis of human AC133 promoters. (A) Functional analysis of promoters P1 and P2 in Caco-2 and NT-2 cell lines. Bars show fold increase in activity of luciferase for the constructs cloned into pGL3-enhancer vector containing promoters P1 or P2, compared with promoterless pGL3-enhancer vector. All data represent the mean of at least 3 independent experiments. (B) Functional analysis of human AC133 promoter 1 (P1) activity using 5′/3′ deletion constructs in Caco-2 and NT-2 cell lines. Diagram on the left side shows different reporter constructs made from the 5′ flanking region of exon 1A, using primers listed in Table 1. Transcription start point is indicated by +1. Luciferase gene is fused to +10 position of P1 in constructs i, ii, iv, vi, and viii; –250 position of P1 in constructs v and vii. In construct iii, the most active fragment of P1 is placed in reverse orientation, luciferase fused to position –1100. Diagram on the right side shows fold increase in activity of the promoter constructs compared with promoterless pGL3-enhancer vector (construct I). All data represent the mean of 3 independent experiments. Error bars represent standard deviation.