By using this model, they identified ARR3-positive cone precursor cells as the origin of retinoblastoma cells and PI3K/AKT pathway hyperactivation as the driver of retinoblastoma tumor cell growth, and discovered that inhibition of the spleen tyrosine-protein kinase (SYK) reduced retinoblastoma cell proliferation. The gene discussed is ARR3; the disease is retinoblastoma.