Figure 2.

Enhancer-blocking by Drosophila scs and scs′ in human cells as measured by colony formation. Constructs were transfected in triplicate into Jurkat cells and colony number was determined following growth in soft-agar containing G418. Results are presented as mean ± SD, with the colony number for E-P-Neo or E-P-Neo-scs′ normalized to 100. E is E_δ, P is the V_δ1 promoter, 1.35 is a control φx HaeIII DNA fragment, and DJ1.3 is a fragment spanning D_δ3-J_δ1 from the human TCR α/δ locus. (A) Enhancer blocking by Drosophila scs and scs′. The absolute number of colonies for E-P-Neo was 64. (B) Absence of enhancer blocking by a 1.3-kb DNA fragment spanning the D_δ3 and J_δ1. The absolute number of colonies for E-1.3-P-Neo-1.3 was 269.