The proto-oncogene c-fos can be induced in cells to high transcript levels by numerous exogenous stimuli. We show here by S1 nuclease protection assay that mere mechanical disaggregation and incubation at 37 degrees C induces high levels of c-fos hnRNA and subsequently of mature mRNA in neonatal mouse cerebellar tissue. This specific increase of c-fos steady-state levels is dependent on the incubation time with a maximal level of induction (over 40-fold) after approximately 1 h. The accumulation of c-fos transcripts is suppressed by alpha-amanitin while cycloheximide intensifies induction only moderately. Excessive elevation of c-fos mRNA levels is age-dependent and occurs only in early postnatal but not in adult cerebellar tissue. We conclude that the steady-state level of c-fos transcripts is inducible in a development-dependent manner, and thus may be involved in normal neurogenesis of the mammalian cerebellum.