The effect of dexamethasone on human non-small cell lung carcinoma in vitro and in vivo was investigated. Dexamethasone caused a significant reduction in growth rate in most of the cell lines at normal passage densities with the exception of H125 which had an increased growth rate in the presence of dexamethasone. In both cases the effect was dose dependent. Clonogenicity as a monolayer was increased by dexamethasone in all cell lines investigated except H125. Cloning efficiency in agar of all the cell lines examined was reduced by dexamethasone in a dose dependant manner. Significant levels of glucocorticoid receptor were found in all cell lines investigated. PA activity was lowered by dexamethasone in all cell lires except H125 where it was raised though not significantly
