HBEGF and neoplasm: Our results corroborate an earlier in vitro study in which HUVEC endothelial cells were shown to express HB-EGF and promote the migration, in a trans-well migration assay, of EGFR-positive smooth muscle cells toward endothelial cells in an HB-EGF/EGFR-dependent manner,40 as well as an in vivo study from the same group describing decreased pericyte coverage of the tumor microvasculature in transplanted tumors following gefitinib treatment.50