Steroid molecules are derived from a common precursor, cholesterol, the base molecule in the illustration. They share similar chemical properties, notably their lipophilicity, which enables them to pass through cellular membranes without the need for a carrier molecule. Indeed, cholesterol is a normal constituent of cellular membranes. The conversion of cholesterol into the various steroids (e.g., cell-specific enzymes add molecules to the numbered sites on your example). The subsequent MOA of these steroids is similar. They circulate in the blood, pass through the membranes of target cells, bind (dimerize) to intracellular receptors, bind to DNA regulatory elements, and up- or down-regulate gene expression to yield proteins that influence the organism's physiology.