phosphorylated form of the amino-acid L-serine; DL-O-Phospho-DL-serine is the racemic mixture. Both carry a phosphate ester that gives them a high affinity for calcium ions and for group-III metabotropic glutamate receptors (mGluR4/6/7/8).

an immunomodulating agent used topically, mainly in dermatology to treat inflammatory skin conditions such as atopic dermatitis (eczema). It belongs to the calcineurin inhibitor class, which includes tacrolimus, and works by suppressing the immune response that leads to inflammation