Identification of specific MSC clones that express the epithelial cytokeratin, K19. (a) K19 expression was detected in MSC culture by immunofluorescence with a Texas Red-conjugated anti-K19 antibody. Nuclei were stained with DAPI. Original magnification, × 400. (b) Expression level of K19 mRNA in each MSC clone was quantified by real-time PCR. Fold increase in each clone is shown, as compared to the average expression level of all clones. (n = 3 in each clone). (c) Alizarin Red and Oil red-O staining was performed to detect osteoblast and adipocyte differentiation, respectively, in 15 (no. 1 to no. 15) individual MSC clones isolated from the bone marrow of a single mouse, 14 days after treatment with appropriate differentiation medium.