Table 1. ERV-9 LTR enhancer activity is not blocked by the HS5 site in plasmids transiently transfected or stably integrated into K562 cells.

	Plasmid	CAT/GFP level
1.	LTR-CATa	8 ± 1.6
2.	HS5L-εp-CATa	5 ± 2.3
3.	LTR-HS5L-εp-CATa	27 ± 4.5
4.	HS5-εp-CAT	2 ± 0.5
5.	LTR-HS5-εp-CAT	12 ± 2
6.	HS4-εp-CAT	4 ± 1.5
7.	HS5L-HS4-εp-CAT	28 ± 10
8.	εp-CAT	1
9.	HS2-εp-CAT	22 ± 5
10.	HS2-HS5L-εp-CAT	8 ± 4
11.	LTR-GFP	9 ± 3.3 (11± 4)
12.	HS5-εp-GFP	1.2 ± 0.4 (2 ± 0.3)
13.	LTR-HS5-εp-GFP	18 ± 5 (12 ± 0.7)
14.	εp-GFP	1 (1)

HS5L, the 1.2 kb HS5 DNA; HS5, the truncated 0.5 kb HS5 DNA that contained the binding site for CTCF but not for NF-E2 (see Fig. 1a).

CAT levels were averages of three determinations with standard deviations. GFP levels were averages of two determinations. Numbers in parentheses are GFP levels of transiently transfected plasmids.

^aCAT levels were determined in a previous study (19).