Fig. 4.

Putative cancer stem cells show an increased in vitro and in vivo invasive potential and exhibit mesenchymal phenotypes. (A) Examination of invasive ability of sorted CD133⁺ cells utilising a collagen-based cell invasion assay. FBS, fetal bovine serum. (B) Quantification of invading cells. ^*P < 0.001; ^**P < 0.005; OD₅₆₀, Optical density at 560 nm. (C) Western blot analysis of E-cadherin, fibronectin, vimentin and β-catenin, with β-actin as a loading control. (D) Evaluation of in vivo tumorigenesis and invasiveness in a chick embryo model. Bright field image of the chorioallantoic membrane (CAM) 3 days after inoculation with feline mammary carcinoma cells (left panel) and fluorescence image of tumour cells 3 days after inoculation (right panel). Red arrows indicate opaque plaques representative of tumour growth.