Lung metastasis in Spp1+/- mice implanted with MDA231-LM2 cells expressing control shRNA (control), and Spp1-/- mice implanted with MDA231-LM2 cells independently expressing one of two different SPP1 shRNAs (SPP1-deficient). Ex vivo lung luminescence was analyzed, panel H. Boxes show the median value with upper and lower quartiles. Whiskers represent minimum and maximum values. Control n = 16 mice, SPP1 deficient (1) n = 14 mice and SPP1 deficient (2) n = 15 mice. P values were determined by a two-tailed Mann-Whitney test. (I) Representative histological images of metastatic foci (top) and ex vivo lung bioluminescence (bottom). In histological samples, immunohistochemistry was used to determine metastatic nodules based on expression of human vimentin (arrows). Scale bar, 100 µm. 