Named after Roswell Park Memorial Institute (RPMI), RPMI 1640 is a modified version of McCoy’s 5A medium using a bicarbonate buffering system. Originally developed for human leukemia cells in suspension or monolayer culture, it was later found suitable for many mammalian cells, including HeLa, Jurkat, MCF-7, PC-12, PBMCs, astrocytes, and cancer cells. It is especially effective for suspension cultures and is among the most widely used media. Compared with other media, RPMI 1640 contains reduced glutathione and higher levels of vitamins. It also includes biotin, vitamin B12, and p-aminobenzoic acid, as well as elevated choline chloride and inositol, which are absent in EMEM and DMEM.