CTSL and neuroblastoma: More evidence for chemosensitizing effects due to cathepsin inhibition has been provided by the same group more recently by showing that the cathepsin L-selective aldehyde inhibitor iCL (compound 11) led to a reversal of resistance to doxorubicin in human neuroblastoma and osteosarcoma cells in vitro and in nude mice xenografted with doxorubicin-resistant human neuroblastoma cells in vivo (Zheng et al., 2009).