Table I.

Effect of CpG methylation on Acr-modification-induced mutations in the supF gene in normal human lung fibroblasts

Exp.	Acra	CpG Methylationb	White colonies/total colonies	Mutation frequency (×104)	Fold changec	P valued
1	−	−	5/20720	2.4
2	−	−	4/17660	2.3
1	−	+	5/14480	3.5	1.4
2	−	+	6/17920	3.3	1.5
1	+	−	18/8350	21.6
2	+	−	21/9560	22.0
1	+	+	38/7280	52.2	2.4
2	+	+	43/8500	50.6	2.3	0.03522

^aAcr: pSP189 plasmids were treated with Acr (0.5mM) at 37°C for 24h.

^bCpG methylation: pSP189 plasmids were treated wit SssI methyltransterase at 37°C for 1h.

^cFold change of mutation frequency between unmethylation and methylation in each experiment.

^dP value: statistical significance was tested by Student’s t-test.