A cautionary note on the use of stable transformed cells

Gene transfection and ectopic expression is a widely used method in experim ental biology. In the present report, we would like to point out that this approach may, in certain circumstances, lead to a modification of the trans fected cell phenotype. Indeed, we observed that after transfection of bcl-2 gene in the neuronal PC12 cell line some of the selected clones have lost their neuronal and catecholaminergic characteristics, i.e. TH expression an d ability to grow neurites in response to NGF. Thus, the resistance of some PC12-Bcl-2 clones against neurotoxic insults may not necessarily reflect t he potential benefit afforded by Bcl-2 expression. We therefore encouraged authors to verify cell phenotype after stable transfection to avoid misinte rpretation of their results.