Fig. 7. Expression patterns of GFP-N-RAP-IB (A,C) and of -actinin in the same fields (B,D). Cardiomyocytes were transfected with GFP-N-RAP-IB at 2 days and viewed 1 day post transfection. In some cardiomyocytes, GFP-N-RAP-IB is organized in striations resembling the Z-lines of mature sarcomeres (A), even though -actinin is diffusely distributed (B). Note the presence of normal -actinin striations in the neighboring untransfected cell (B). In addition, N-RAP-IB often inhibits myofibril formation (C,D). In this example, N-RAP-IB is localized at cell-cell contacts and cytoskeletal structures resembling myofibril precursors (C), but the transfected cell exhibits far fewer striations than neighboring cells (D).