One of the most common causes of progressive RP is mutations in the human gene that codes for a protein called CRB1. These gene mutations cause photoreceptors to come loose from nerve cells in the eye, called Müller glia cells. Insights gained from insects often shed light on conditions in humans. As such, a similar gene product in fruitflies, called Crumbs, offers scientists an attractive target for studying the biochemical pathways of this disease. An EU-funded project called 'Restoring Mueller glia cell photoreceptor interactions with Crumbs' (CRUMBS IN SIGHT) studied the interactions of the Crumbs protein with other important proteins in the retina. The project brought together researchers at 6 institutions and included a partnership with industry. Researchers gained a much improved understanding of Crumbs and CRB1, as well as how these proteins keep Müller glial cells and photoreceptor cells together in the retina. The researchers also identified reliable biomarkers for early diagnosis. Two potential cures were investigated: cell transplants and gene therapy to restore normal CRB1 cells in Müller glia cells. Both methods showed potential and a partnership with an Amsterdam-based company was formed to commercialise the gene therapy approach. RP is a debilitating disease that remains untreatable. The CRUMBS IN SIGHT project has provided a comprehensive understanding of the cause of disease, as well as hope for a cure.