CASP3 and neoplasm: Retinal organoids staining positively with the RXRG cone marker (day 65–70; Fig. 6A–H) were incubated with vehicle, sunitinib, topotecan, or melphalan [at the IC50 for tumor organoids for 24 h (Fig. 5C)], and cell death was examined by immunostaining of cleaved caspase 3 (CC3), a marker of apoptosis.