Table 1.

Responses of the wild-type, DNA-PKcs−/−, Atm−/−, and p53−/− mice after 10 Gy of IR

	Wild type	DNA-PKcs−/−	Atm−/−	p53−/−
p53*	++++	++	Not detectable	Not detectable
p21*	++++	++/+++	+	Not detectable
Bax*	+	−	+	−
G1/S arrest†	Normal	Normal	Deficient	Deficient
Apoptosis‡	Normal	Deficient	Normal	Deficient

^*Wild-type, DNA-PKcs−/−, Atm−/−, and p53−/− mice were exposed to 10 Gy of whole-body γ-irradiation. Two and/or four hours after IR, mice were sacrificed by asphyxiation, the thymuses dissected and thymocytes prepared. Immunoblotting was performed by using standard techniques and antibodies specific to p53, p21, and Bax, respectively. Signals of p53, p21, and Bax expression were quantified using AMBIS scanning densitometer and software. Relative increase of p53, p21, and Bax expression after IR is expressed as follows: ++++: greater than 4-fold increase; +++: 3- to 4-fold increase, ++: 2- to 3-fold increase, +: less than 2-fold increase; −: no change or decrease in protein expression after IR. 

^†See Fig. 2. 

^‡See Fig. 1.