Cell migration, aggregation and proliferation in different conditions. Fluorescence images of: A) BOKL in direct co-culture with BMSCs (arrow indicates a cell cluster), B) BOKL cultured in CM BMSCs, C) BOKL in co-culture with MRC-5 and D) BOKL in GM. All the images have been taken after 3 days of culture. E) Quantification of the cell aggregation, expressed as the average number of clusters normalized per total cell number. Clusters were defined as groups of at least four cells in contact, as already reported for micrometastasis . ***: p < 0.001, **p < 0.01 vs. other conditions. F) Quantification of the directionality of the cell movement, expressed as index P. P is defined as A1/A2, where A1 is the distance between the position of the cell in the last image and that in the first. A2 is the sum of distances travelled by the cell in all the images . Values of P near 1 indicate a directional movement. **: p < 0.01 vs. other conditions. G) Proliferation of BOKL after 3 days of direct co-culture with BMSCs or MRC-5 and after 3 days in culture with conditioned medium from BMSCs (CM) or control medium (CTR), ***: p < 0.001. All error bars represent standard deviations of at least three different experiments.