KIF3A and infection: To enable sufficient expression of transfected genes, we used a double infection system consisting of tetracycline trans-activator (tTA) under the control of L7 promoter30 and GFP, GFP–P2A–KIF3A, or GFP–P2A–KIF3C under the control of tetracycline response element (TRE) promoter, as shown in Fig. 5A.