Table 1.

Correction of an HPRT⁻ mutation by homologous recombination

HPRT− cell type	Cell no., ×10−7	Input CFC, ×10−5	HATr colonies, no.	Correction frequency, ×105
BM (Hprtb-m3)	7.3	1.5*	9	6.0
BM (Hprtb-m3)	12	2.4*	10	4.2
BM (Hprtb-m3)	8.5	0.3†	0	NA
BM (Hprtb-m3)	12	4.8†	8	1.7
BM (Hprtb-m3)	10	2.5†	3	1.2
BM (Hprtb-m3)	10	1.2†	11	9.2
				4.4 ± 3.3‡
ES (HM-1)	2.0	NA	420	2.1
ES (HM-1)	1.5	NA	300	2.0
ES (HM-1)	2.0	NA	564	2.8
				2.3 ± 0.4‡

CFC, colony-forming cells; HAT^r, HAT resistant; and NA, not applicable. 

^*Assuming 200 CFC/10⁵ BM cells, as calculated from the data in Fig. 1A. 

^† Number determined directly by a clonogenic assay without HAT selection. 

^‡ Means ± standard deviation.