MAPK1 and breast cancer: The reduced invasiveness was also confirmed by the down-regulation of p-ERK2 and cyclin D1 expression in the cancer cells co-cultured with MDAPSF, as shown in the Western blot analysis in Figure 5B. The same experiments were performed for co-culturing the breast cancer cells in the presence of MDABM spheres, previously cultured for three days in the BM array (as schematized in Figure 5C).