Figure 4: a) Outgrowth of the SKBR3 cells from the bone fragment (BF) in which they penetrated following the co-culture experiments. The new cell population sprouting from the bone fragments is named SKBR3–B1, where B1 stands for “bone conditioned”; b) The progressive three-dimensional overgrowth of SKBR3-B1 cell colonies derived from the bone colonization.