It is of note that sorafenib is a kinase inhibitor with multiple targets and can inhibit both vascular endothelial growth factor receptor (VEGFR-2) and receptor tyrosine kinase (EphB4).23 Furthermore, as determined by HPLC, treatment of tumour cells (A549) or normal cells (HEK293) with a 1:1 mixture of precursor molecules for 24 h generated a chromatographic peak of self-assembled PROTAC. Here, NTRK1 is linked to neoplasm.