LDLR and neoplasm: At 6 h post administration of a single dose of 3H-SQGem NPs, the percentage of radioactivity in the tumour was twofold higher in tumour xenografts originating from MDA-MB-231 (high level of LDLR) cells than in xenografts originating from MCF-7 (low level of LDLR) (Supplementary Fig. 17).