TKT and thyroid gland undifferentiated (anaplastic) carcinoma: We found that GCV treatment significantly (p<0.05) decreased the Rluc activity of anaplastic thyroid cancer cells (CAL62/Rluc) in MSC-Tet-TK and MSC-TK co-injected site (right) compared than MSC co-injected (left) site (Fig 8A and 8B).