Oredsson et al. (2025) present a comprehensive protocol for the use of the Oredsson Universal Replacement (OUR) medium, a xeno-free, chemically defined, open-source medium designed for culturing a range of human normal and cancer cell lines. The protocol outlines procedures for thawing, culturing, and freezing cells in a reproducible and serum-free environment. Although the study does not directly compare OUR medium with FBS or hPL, it reports that the performance benchmarks for CD4+ T cells, Jurkat, and THP-1 cultured in OUR medium were consistent with existing literature. Here, CD4 is linked to cancer.