Table 2.

Description of ribosomal gene arrays of the fibroblast cell lines studied.

Cells	Donor age	rDNA CN ± SE		M ± SE
		Leukocyte	Fibroblast (5 p)	Leukocyte	Fibroblast (5 p)
HSF–45∗	35	430 ± 50	450 ± 40	1.1 ± 0.2	1.0 ± 0.1
HSF–53	21	390 ± 40	370 ± 20	1.0 ± 0.1	1.2 ± 0.2
HSF–57	52	570 ± 30	590 ± 40	2.1 ± 0.2	1.7 ± 0.2
HSF–61	52	480 ± 40	470 ± 60	1.2 ± 0.1	1.1 ± 0.2
HSF–66	35	640 ± 40	670 ± 70	2.2 ± 0.2	1.9 ± 0.2

^∗The digits in each line denotation indicated the order number of the final passage, after which the cells stopped their division. rDNA CN, rDNA copy number; SE, standard error.