The scientists observed the drug at work in animal cells. After modifying a number of cells to remove certain proteins, they realised that the drug had different effects.
The development of APL is characterised by the fusion of the proteins promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARa), causing the cells to become cancerous or leukemic.
The scientists found that arsenic helps molecules called SUMO to stick onto the fused protein involved in leukaemia. An enzyme called RNF4 then 'pursues' the SUMO molecules, successfully breaking down the fused PML-RARa protein that causes the cancer.
