MK2 signaling differentially regulates osteoclast size and number from defined OCP cells.

<p>Cells were fixed, TRAP stained, and visualized by light microscopy. (A) Representative 100x images of female (top) and male (bottom) mouse bone marrow cells defined by CD11b surface expression driven to form osteoclasts (OCs) with M-CSF (25ng/mL) and RANKL (50 ng/mL). Female OCs (black arrow) were magnified 3x and inset (top). TRAP positive cells with three or more nuclei (OCs) from (B) female and (C) male mice were enumerated from three random images at days 3 (top) and 5 (bottom) of RANKL treatment. Osteoclast size from female (B, right) and male (C, right) was measured by pixels per osteoclast using Adobe PhotoShop CS. Data are expressed as means ± SE compared to <i>Mk2</i>^<i>+/+</i> controls (*<i>P</i>≤0.05, **<i>P</i>≤0.01, ***<i>P</i>≤0.001).