CD44 and breast cancer: Given the increased HA synthesis of MSC in response to MDA-MB-231 breast cancer SN and that HA is able to connect cells via binding of the HA strands to its receptors (CD44, RHAMM, LAYN) we went on to investigate whether a transmembranous HA receptor on the MDA-MB-231 cells might be responsible for the communal migration of the two cell types.