Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40880-018-0344-6/MediaObjects/40880_2018_344_Fig1_HTML.png)
Longitudinal circulating tumor DNA sequencing provides novel insights into gene alterations underlying trastuzumab resistance in HER2-positive metastatic gastric cancer. HER2+: HER2-positive; mGC: metastatic gastric cancer; ctDNA: circulating tumor DNA: Copy No.: copy number