Olbrich, T. et al. Cell Rep. 28, 597–604 (2019).

A diploid genome is an asset in many ways, as it ameliorates the effect of mutations and ensures genetic diversity. But having two copies of each gene is less ideal if the goal is to knock genes out to test their function in forward genetic screens. Somatic haploid cell lines, such as HAP1 isolated from a leukemia patient and converted to adherent cells, are a great resource that gets around the problem of having to target two copies, but they are not easy to maintain in culture. Haploid cells quickly revert back to their more stable diploid state. Olbrich et al. performed a chemical screen on 977 compounds to find candidates that can maintain HAP1 cells in their haploid state. They found 10-deacetylbaccatin-III (DAB), a natural chemical isolated from the yew tree and precursor to a drug used to treat a parasitic disease in cattle, to be most effective in maintaining haploidy. DAB also proved effective in selecting for diploid cells in a mixture of 2n and 4n cells. DAB affects microtubule dynamics and leads to a prolonged arrest during mitosis; the higher the ploidy of a cell, the longer the mitotic arrest, which is often followed by cell death.