ELANE and neoplasm: Recently, Yingyuad et al. described new PEGylated siRNA-nanoparticles activated by human leukocyte elastase (HLE) or matrix metalloproteinase-2 (MMP-2), both present in the extracellular spaces of tumor in order to promote invasion and metastasis of cancerous cells via degradation of basement membrane and extracellular matrix barrier.