Quantification of eIF2α Phosphorylation Associated with Mitotic Catastrophe by Immunofluorescence Microscopy

Mitotic catastrophe is an oncosuppressive mechanism that drives cells toward senescence or death when an error occurs during mitosis. Eukaryotic cells have developed adaptive signaling pathways to cope with stress. The phosphorylation on serine 51 of the eukaryotic translation initiation factor (eIF2α) is a highly conserved event in stress responses, including the one that is activated upon treatment with mitotic catastrophe inducing agents, such as microtubular poisons or actin blockers. The protocol described herein details a method to quantify the phosphorylation of eIF2α by high-throughput immunofluorescence microscopy. This method is useful to capture the 'integrated stress response', which is characterized by eIF2α phosphorylation in the context of mitotic catastrophe.