E1A-NR.3 was established by immortalization of postnatal day 6 rat neuroretinal tissue using the psi2 replication incompetent retroviral vector. As a result, these cells are already resistant to geneticin/G418 and would require an alternative selection marker for transfection studies. These cells were designed not to form tumors in animals.E1A-NR。采用psi2复制不合格逆转录病毒载体对出生后6天大鼠神经视网膜组织进行永生化。因此,这些细胞已经对geneticin/G418具有抗性,需要另一种选择标记来进行转染研究。这些细胞被设计成不会在动物体内形成肿瘤。