Amplification of Growth Inhibition by Glucocorticoid on L5178Y and Li 2i 0 Lymphoblasts in Vivo1

apparent with a physiological level of glucocorticoids of about 0.3 @tMin humans, as shown in experiments on hepatoma cells (4) and L5i 78Y cells(6)in vitro,Factor1 maypossiblyenhance the effect of physiological levels of glucocorticoid in vivo and thus may itself have the therapeutic effects of glucocorticoid. In this work, we examine (a) the effect of Factor 1 on the growth inhibition by glucocorticoid of the solid form of L51 78Y cells and the ascitic form of Li 210 mouse lymphoblasts in vivo and (b) whether Facton i itself enhances the effect of physio logical levels of glucocorticoid sufficiently to inhibit growth of these lymphoblasts in vivo in order to investigate the clinical use of Factor 1 instead of glucocorticoid.