Effects of IKKα knock-down on Runx2 protein levels in human OA chondrocyte micromass cultures are independent of its kinase activity.

<p>Runx2 immunostaining in 3-week pellet cultures of primary human OA chondrocytes: WT (GL2 control), IKKα KD cells with empty BIN retroviral vector and IKKα KD cells with kinase-dead murine IKKα(K44M)-BIN. Global views of micromass sphere sections (100Xmagnification) are shown on the left, and three random fields at 400Xmagnification submitted to quantitative image analysis are on the right. Antibody stained images are shown in the right side upper rows (labeled 1, 2 & 3), with each 400Xfield analyzed by Nikon Imaging Software in the lower rows (labeled 1.1, 2.1 & 3.1). For each sample an IHC staining threshold was established based on an antibody isotype control. Antibody staining is in red in conjunction with hematoxylin (blue) nuclear counterstaining. Data are representative examples of multiple sections of micromasses prepared with ACs of 3 OA patients; and results of all such experiments are presented as statistically analyzed bar graphs in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073024#pone-0073024-g007" target="_blank">Figure 7E</a>.