in a given fruit may be not extrapolated to a different species. Cell wall materials obtained from untreated and calcium-treated 'Celeste' sweet cherries were fractionated and analysed after cold storage, and related enzyme activities and gene expression were assessed. Calcium-treated fruit were firmer, with lower weight loss and decay incidence than the controls. The accumulation of PaβGal and PaEXP1 transcripts was strongly inhibited in cold-stored fruit, although expression levels recovered largely after three days of shelf life. Data suggest that pectin methylesterase, β-galactosidase and expansin activities may control the access of additional proteins to their substrates. A possible role for the apoplastic redox status in the modulation of the process is also discussed