Used in cell culture media as a precursor for purine synthesis, supporting the growth of certain cell lines that cannot synthesize purines de novo. Commonly found in hybridoma and monoclonal antibody production processes. Also serves as a component in selective media for microbial cultivation, particularly in combination with aminopterin and thymidine in HAT selection medium. Its solubility as the monosodium salt enhances stability and bioavailability in aqueous solutions.