Kinetics of MSCs homing to erbB2-expressing ovarian tumors. MSC-GFP and MSC-AR labeled with firefly luciferase were injected ip in SCID mice bearing SKOV3ip1 ovarian tumor xenografts at 2×10^6 cell/mouse. Tumors were collected at 4, 8, 24, 48 hrs and luciferase expression was measured by imaging of excised tumors (A) and by luciferase assay of tumor lysates (C). Representative photographs of mouse organs (B, upper panel) and the same organs with overlaid bioluminescent signal (B, lower panel) are presented. Arrows connect black and white image of organ and corresponding image of the same organ with superimposed bioluminescent signal (D) Ratio of MSC numbers detected in tumor versus liver were determined for mice euthanized after 24 hrs after MSC injection. White bar is tumor/liver ratio for MSC, black bar is tumor/liver ratio of MSC-AR.