PKD2L1 and retinal degeneration: Interestingly, eupatilin altered the expression of essential phototransduction genes involved in several forms of retinal degeneration, including CRB1, EYS, SAG, GRK7, RPGRIP1, USH2A, PROM1, ARR3, PDC, PDE6A, GNGT1, and GUCA1C; the photoreceptor cation channels CNGA1 and CNGB1; and the cilia transmembrane protein genes PKHD1, PKD2L1, PCDHB15, CDH23 (USH1D), and PCDH15 (USH1F) (Figure 5E).