To determine if R-RAS2 is functionally downstream of CD44 promoting BC cell migration, we engaged in a series of transwell assays in Boyden chambers in which CBM-MBC21 cells migrated from serum-free medium in the upper chamber to the serum-containing medium in the lower chamber passing through pores of 8 μm-diameter and through matrices of different composition. The gene discussed is RRAS2; the disease is breast cancer.