Identification of cis-regulator elements active on the TLX promoter active in T-cell lines. (A) Transcriptional regulatory activity of HSSs 1 to 5. Fragments encompassing the HSSs were subcloned in pGL3 (S-pGL3: containing an SV40 promoter) and tested by transient transfection in HPB-ALL. Luciferase activities are in arbitrary units (AU) and not normalized. (B) Fragments from H3 and H4 were tested for transcriptional activity using S-pGL3 luciferase reporter vector in HPB-ALL (T-ALL; left panel) and Nalm6 (BCP-ALL; right panel) cell lines. Three different concentrations of vector were used. Values are indicated as fold of activation with respect to 0.5 μg S-pGL3 vector independently in each cell line. Data were normalized using a β-galactosidase reporter. (C) H3* and H4* are active on SV40 (left panel) and TLX3 (right panel) promoters. Normalized values are indicated as fold of activation with respect to 0.5 μg S-pGL3 vector (left panel) or 0.5 μg T-pGL3 (right panel). The nucleotide sequence of fragments H3* and H4* is shown in Figure S5. Error bars indicate standard deviations.