TABLE 1.

Methylation in the p16 CpG island

Cell culture, passage, and gene expressed	PCR product (CpG cytosinesa)								Mean no. of methylated sites per 47 total CpG sitesb
	A (1–15)				B (13–47)
	No. of PCR clones sequenced	No. of methylated CpG sites/clone			No. of PCR clones sequenced	No. of methylated CpG sites/clone
		Meanc	Median	Range		Mean	Median	Range
HMEC9
3	10	0.1 (0.0, 0.3)	0	0–1	10	0.5 (0.0, 1.1)	0	0–2	0.6
8	9	0.2 (0.0, 0.5)	0	0–1	9	0.2 (0.0, 0.5)	0	0–1	0.4
16, E6	10	2.9 (1.5, 4.3)	2	1–8	11	9.1 (7.0, 11.2)	9	5–16	11.8
29, E6	7	2.9 (1.7, 4.1)	3	1–5	10	13.6 (12.2, 15.0)	14	10–16	16.2
42, E6	10	4.6 (2.5, 6.7)	3.5	1–11	12	19.2 (15.4, 23.0)	20	9–28	23.0
32, E6/E7	10	0.0 (0.0, 0.0)	0	0	10	0.2 (0.0, 0.5)	0	0–1	0.2
HMEC6
3	10	0.0 (0.0, 0.0)	0	0	11	0.4 (0.0, 0.8)	0	0–2	0.4
12, E6	10	2.0 (0.7, 3.3)	1	0–5	12	9.3 (7.2, 11.4)	8.5	6–17	10.9
25, E6	10	2.1 (1.1, 3.1)	2.5	0–4	12	19.2 (16.4, 22.0)	19	9–25	20.6
HMEC4
5	10	0.9 (0.0, 2.1)	0	0–5	10	0.7 (0.0, 1.5)	0	0–3	1.5
12	10	1.5 (0.4, 2.6)	1.5	0–4	12	8.3 (4.7, 11.9)	8.5	0–17	9.5
18	9	2.9 (2.3, 3.5)	3	2–4	12	5.4 (3.2, 7.6)	6	1–11	7.7
H249	4	0.0 (0.0, 0.0)	0	0	4	0.0 (0.0, 0.0)	0	0	0.0
H1618	3	14.7 (13.3, 15.0)	15	14–15	4	35.0 (35.0, 35.0)	35	35	46.9

^aCpG cytosine numbers correspond to those in Fig. 1, 2, 4, and 5. 

^bCalculated by adding the methylation frequency per clone at each of the 47 sites (the methylation frequencies at CpG sites 13 to 15 were calculated with data from both PCR product A and B clones). 

^cNinety-five percent confidence intervals of the means are shown in parentheses.