In order to study the effect of the active metabolites 5-FU, 4-HC and the 5-FU+4-HC combination treatment on invasive potential of 231/LM2-4 breast cancer cells, we used two in vitro three-dimensional (3D) assays as surrogates for in vivo tumor cell invasion: a transwell chemoinvasion assay using collagen type IV, and a 3D laminin-rich extracellular matrix (lrECM) “on-top” assay employing Matrigel as a barrier. The gene discussed is LAMB2; the disease is breast carcinoma.