Effects of marathon on bax and bcl-2 mRNA expression. A) bax and bcl-2 RNA content was estimated by Northern Blot. RNA was extracted, electrophoresed and hybridized with a labelled probe for bax and bcl-2 as described under Methods. β-actin was used as loading control. Blots are representative of at least three separate experiments. (P < 0.0001). B) bax: bcl-2 ratio in samples before marathon and after marathon was obtained by densitometry analysis of the blots shown in A. C) Change bax: bcl-2 ratio in samples before and after marathon.