RAC2 and breast carcinoma: However, the consistent upregulation of RAC2 and KRAS exRNAs in serum and mRNAs in tissue in breast cancer patients as compared to normal donors, together with the known roles of these 2 members of the Ras proto-oncogene superfamily in breast cancer etiology, suggest that a subset of the observed serum exRNA expression changes relate to the disease rather than the treatments.