Inhibition of JNK induces mitotic arrest.

<p>(A, B) Representative confocal photomicrographs of immunohistochemistry for phospho-JNK (red) and phospho-histone-H3 (green) in sections of retinal tissue maintained for 3 hours <i>in vitro</i> either in absence (A - CTR) or presence of SP600125 (B - SP). The sections were counterstained with DAPI (blue). Arrows indicate examples of phospho-histone-H3 positive cells. Scale bar: 20 µm. (C) Numbers of phospho-histone-H3 stained cells per 100 µm of linear extent parallel to the retinal surface, along the mitotic stratum of retinal explants maintained <i>in vitro</i> for 3 hours either in the absence (CTR - black column) or presence of SP600125 (SP - gray column). *** <i>P</i><0.001 versus CTR. (D–F) Representative confocal photomicrographs of mitotic cells immunolabeled for phospho-JNK (red) in sections of retinal tissue maintained for 3 hours <i>in vitro</i> in the presence of SP600125. The sections were counterstained with DAPI (blue). Stages of mitosis are indicated as either prophase/prometaphase (p) or metaphase (m), while arrows show aberrant chromosome morphology. Compare the disorganized chromatin with the profiles shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034483#pone-0034483-g004" target="_blank">fig. 4</a>. Scale bar: 5 µm. (G) Frequency of prophase/prometaphases (PRO), metaphases (META), anaphases (ANA) and aberrant profiles (ABE) among all mitotic cells in the outer margin of retinal explants maintained <i>in vitro</i> for 3 hours either in the absence (CTR - black columns) or presence of SP600125 (SP - gray columns). Data are means±S.E.M. pooled from at least 250 mitotic cells in each of six independent experiments. CTR - control; SP - SP600125; NBL - neuroblastic layer. ** <i>P</i><0.01 versus CTR.