Frozen aliquots of mammalian cells which are ready-to-use like a reagent. There is no need to cultivate the cells before. The recovered ARCs are dispensed directly into an assay plate and processes as usual. The high consistency of the pre‐validated cells helps to increase the reproducibility and reliability of any cell-based assay. ARCs are available from various mammalian cell lines and provided at 10 million cells per vial together with recovery buffer and assay medium.