The incidence of cell death due to radiation was examined in a neonatal in
vivo model. Differences in the induction of apoptosis, amount of cell proli
feration, S-phase cell death, Bcl-2 and p-53 expression could best be expla
ined by the differences in the zonal state of differentiation and developme
nt. The present in vivo model may thus be useful in testing radiation thera
pies for renal cancer.