Named for the site at which it was developed, the Roswell Park Memorial Institute, RPMI 1640 is a modification of McCoy's 5A containing an increased level of inositol. Examples of cell types for which this medium is appropriate include mammalian myeloma and hybridoma cells such as mouse hybridomas, human leukocytes, and B and T lymphocytes. RPMI 1640 is also used for suspension cultures or monolayer human leukemic cells.