OBJECTIVE: Investigating whether extracellular factors are possible actors in tumoral progression in bladder carcinoma. METHODS: RT112/G2 bladder tumour cells were grown in presence of TGFbeta and analysed by immunological and cDNA microarray techniques. RESULTS: TGFbeta inhibited cell proliferation, reduced TNFalpha- and IFNgamma-induced apoptosis by decreasing TNFalpha-RI and IFNgamma-R antigen expression. It also inhibited cleaved caspase 8 and 9 expression, decreased E-cadherin, and increased BclxL and cyclooxygenase-2 expression. The cDNA microarray approach showed that TGFbeta up-regulated the expression of genes with defined roles in tumoral progression sometimes associated with poor outcome in bladder cancer. CONCLUSION: These results suggest that a part of the bladder tumoral progression process may be related to the action of exogenous TGFbeta confirming the possible role for the microenvironment.