TYMS and breast carcinoma: have demonstrated that co-administration of 5−FU with VPA or SAHA as an inhibitor of histone deacetylases could downregulate the expression level of TS in 5−FU−resistant MDA−MB−468 breast cancer cells, and thereby promoting the sensitivity of both 5-FU-sensitive and −resistant breast cancer cells to 5-FU chemotherapy (174).