ADCYAP1 and retinoblastoma: As PACAP is shown to be involved in certain tumorous transformations [55] and changes in PACAP and PAC1R can be detected under pathological conditions [34,35], this study aimed to investigate potential alterations in the expression of PACAP38 and PAC1R within tumor tissue samples obtained from enucleation specimens of retinoblastoma patients and the effect of PACAP38 treatment on the survival of human Y-79 retinoblastoma cells.