Table II. Combined Q-FISH and spectral cytogenetic analysis (SKY) of primary MEFs from all different genotypes.

Genotype	No. of meta	RT-like fusionsa		DCa	RT + DCa	Breaks at Chrb	Gaps at Chrb	No. of fragments	Breaks + gaps +
	phases	TTAGGG	No TTAGGG						fragmentsa
Terc+/+/Ku86+/+ (129)	54	0.018a (8–10)c	0.0	0.0	0.018				0.0
G1 Terc–/–/Ku86+/+ (123)	40	0.0	0.0	0.0	0.0	6		4	0.125
G2 Terc–/–/Ku86+/+ (41)	26	0.0	0.04 (16–16)	0.0	0.04	7		1	0.077
G3 Terc–/–/Ku86+/+ (161)	51	0.0	0.02 (?–? H)	0.0	0.02				0.0
G4 Terc–/–/Ku86+/+ (82)	44	0.045 (9–15; 19–15)	0.068 (5–5; 17–17; 14–14)	0.0	0.113			1	0.023
Terc+/+/Ku86–/– (126)	61	0.066 (3–5; 9–12; 10–13; 17–19)	0.0	0.016 (10–10)	0.082		17; 13; 16		0.049
G1 Terc–/–/Ku86–/– (122)	28	0.18 (1–6; 7–13; 7–13; 7–13; 12–15)	0.0	0.036 (4–11)	0.216	12; 16; ?		7	0.36
G2 Terc–/–/Ku86–/– (43)	69	0.029 (11–16; ?–? NH)	0.015 (15–15)	0.0	0.054		10; ?	8	0.145
G2 Terc–/–/Ku86–/– (46)	50	0.06 (17–16; 6–17; 7–16)	0.0	0.0	0.06			3	0.06
G3 Terc–/–/Ku86–/– (160)	35	0.057 (7–11; 9–13)	0.0	0.0	0.057			4	0.114
G4 Terc–/–/Ku86–/– (50)	61	0.066 (9–7; 1–9; 5–12; 10–14)	0.0	0.016 (7–7)	0.082	2; 4; 7; 8; 3; 19	4; 7; 9; 10; 16	9	0.328

^aValues are frequencies per metaphase.

^bChromosome showing the break or the gap.

^cThe chromosomes involved in each fusion are indicated in parentheses: e.g. (8–6), fusion involving chromosomes 8 and 6.

? H or NH: homologous or non-homologous chromosome fusions in which the chromosome identification was not completely achieved by SKY.

MEFs 126 and 129; 122 and 123; 41, 43 and 46; and 160 and 161 are derived from littermates.