LRP1 and neoplasm: However, in in-vitro cell culture, most cancer cells express little or no LRP-1 protein, although LRP1 expression may increase greatly in xenografts in severe combined immunodeficient (SCID) mice; LRP1-silenced cancer cells formed tumours that metastasised to the lungs in SCID mice, but the metastases failed to enlarge, suggesting a cell growth or survival deficiency (Montel et al, 2007).