Table 1.

Animal group divisions.

week	2 week	4 week	8 week	12 week	24 week	36 week
group	M1	M2	M3	N1,M4,M5	N2,M6	N3,M7
	M1: 2-week cigarette smoke (CS) exposure group 1 (n = 12)
	M2: 4-week CS exposure group 2 (n = 12)
	M3: 8-week CS exposure group 3 (n = 12);
	N1: 12-week normal group 1 (n = 8)
	M4: 12-week CS exposure group 4 (n = 12)
	M5: 8-week CS exposure + 4-week CS exposure cessation group (n = 12)
	N2: 24-week normal group 2 (n = 8)
	M6: 24-week CS exposure group 6 (n = 12)
	N3: 36 -week normal group 3 (n = 9)
	M7: 36-week CS exposure group 7 (n = 12)