In a 2021 follow-up study, the American team showed that intravitreal CLU suppressed the upregulation of neuronal nitric oxide synthase (nNOS), a known cause of cone photoreceptor death, in RP retinas of a transgenic rat model (Rhodopsin S334ter-line-3) [245]. The gene discussed is RHO; the disease is retinitis pigmentosa 1.