ABCA4 cDNA expressed in the pCMV6-AC-GFP vector was purchased from OriGene Technologies. Two ABCA4 mutations, A1038V and G1961E, were generated using a QuikChange Lightning Site-Directed Mutagenesis Kit (Agilent Technologies] [5 ]. Flp-In human embryonic kidney (HEK] 293 cells (Catalog#CRL-1573, Life Technologies] were cultured in Dulbecco’s minimal essential medium (DMEM) (Life Technologies] containing 10% fetal bovine serum (FBS), with penicillin (100 U/ml], streptomycin (100 μg/ml), and Zeocin (100 μg/mL) at 37°C in 5% CO2. The stable cell lines were generated as described previously [5 ]. We would state that all experiments were conducted with GFP tagged ABCA4. In our past experiments tagged CFTR behaved similarly to untagged versions [11 (link)–13 (link)].