FLT1 and neoplasm: Although the mean tumour total VEGFR-1 protein level (assessed by immunoblotting of tumour lysates normalised to paired tumour actin levels) was significantly reduced in chaetocin-treated tumours relative to diluent-treated controls, the corresponding mean phospho-VEGFR-1 level did not differ between the groups (Figure 6C), suggesting that the observed differences in tumour vascularity were not likely attributable to differential VEGFR-1 activation.