LRP1 and neoplasm: For example, binding of tPA to low density lipoprotein receptor-related protein (LRP)-1, a scavenger receptor, known to regulate cell spreading, receptor-mediated endocytosis and lipid homeostasis [34,35] induced expression of MMP-9 in a MEK1 and ERK 1/2 dependent manner [36], contributing to ECM degradation, tumor progression and spreading [37].