A water-soluble form of the endogenous hormone cortisol that can bind to glucocorticoid receptors, initiating the transcription of anti-inflammatory and immunosuppressive mediators and inhibiting proinflammatory cytokine activity (IC50 = 6.7 μM for IL-6); commonly used to supplement media for long-term epithelial or endothelial cell cultures and to differentiate pluripotent stem cells