Table 1.

Types of mutations in the coding region of the hprt gene in RAW264.7 cells stimulated to produce NO

Type of mutation	Frequency of mutation, %
	No stimulation	IFN-γ, 23 days	LPS + IFN-γ, 4 days	LPS + IFN-γ + NMA, 4 days
RT-PCR product present	32	41	43	26
Base substitution	22	18	15	11
Small deletion	0	6	5	0
Insertion or truncation	0	2	2	0
Single exon deletion	10	13	12	9
Multiple exon deletion	0	2	9	6
RT-PCR product absent	68	59	57	74
Total mutants analyzed	84	128	58	54