Fig. 4.

A subset of Trp53^CKO fiber cells fail to exit the cell cycle, but express fiber-cell-specific markers. P3 lenses were stained with antibodies that label markers of cell proliferation, cell cycle exit and lens fiber cell differentiation. (A) Labeling for Ki67, a marker for actively cycling cells, is restricted to the anterior epithelium of Trp53^WT lenses. (B) In Trp53^CKO lenses, a few cortical fiber cells are Ki67 positive (arrowheads). (C) BrdU is only incorporated into anterior epithelial cells in Trp53^WT lenses. (D) A few Trp53^CKO fiber cells are BrdU positive (arrowheads). (E) p57^KIP2, a marker of cell cycle exit, is strongly expressed in all nuclei in the lens equator of Trp53^WT lenses. (F) Most cells in Trp53^CKO lenses have nuclei that are stained with antibody to p57^KIP2, but a few nuclei are p57^KIP2 negative (arrow). (G) Ki67 labeling is lost near the equator, where the fiber-specific transcription factor, Maf (c-Maf) is first expressed. (H) Fiber cells in Trp53^CKO lenses express Maf, although some are also Ki67 positive (arrowhead). (I) MIP, a major component of fiber cell membranes, is strongly expressed throughout the fiber zone of Trp53^WT lenses. (J) MIP is strongly expressed in Trp53^CKO fiber cells, even when they express Ki67 (arrowheads).