RET and breast cancer: Neither lapatinib (a dual TKI of EGFR and HER2) nor vandetanib (a TKI of RET) had a substantial effect on the phosphorylation of any of the RTKs or their downstream signalling molecules in EBC-1 or H1993 cells (Figure 1B), whereas these drugs inhibited their specific target RTKs in HER2 amplification-positive breast cancer cell lines (SK-BR3 and BT-474) or RET mutation-positive medullary thyroid carcinoma TT cells, respectively (Figure 1C).