Given the lack of effect of Vandetanib on cell proliferation in mouse tumors, we examined how Vandetanib impacted the proliferation of cultured MTC cells derived from our mouse model (MTCp25OE) [16] as well as two cell lines derived from non-RET mutated sporadic human MTC (MTC-SK and SIN-J) (Figure 3A) [17, 18]. The gene discussed is RET; the disease is medullary thyroid gland carcinoma.