Scientists rely on antibodies, proteins produced by the mammalian immune system, which are able to identify very specific molecules. Day 233 of #LMB365 shows Saša Šviković, from Julian Sale’s lab in the PNAC division, purifying antibodies from litres of cells grown in the lab by passing them through a column able to trap them. This approach has been used extensively ever since César Milstein and Georges Koehler (both PNAC alumni) developed technology to produce monoclonal antibodies, for which they won the Nobel Prize in 1984. The antibodies will be used to investigate how cells respond to various obstacles encountered during the duplication of DNA