We showed that, in a 3D rBM overlay cell culture system, downregulation of Rap1Gap via RNAi in MCF10.DCIS cells led to increased activation of extracellular regulated kinase/mitogen-activated protein kinase (ERK/MAPK), the formation of outgrowths, and increased invasion [170]. Here, RAP1GAP is linked to ductal breast carcinoma in situ.