MMP1 and lung adenocarcinoma: Another study of X. Lou et al. harnessed the power of spheroids to evaluated matrix metalloproteinase-1 (MMP-1) and VEGF as indicators of the interaction between tumor and stromal cells, employed the 3D cell co-culture collagen gel model, containing human lung adenocarcinoma cells (HCC), human lung fibroblast cells (MRC-5) and macrophages [80].