PCSK9 and osteosarcoma: To evaluate the selectivity of 31e towards other cancer cells and normal human cells, the antiproliferative activities against Pc9 (human non-small cell lung cancer cells), Hela (human epithelial cervical cancer cells), SJSA1 (human osteosarcoma cells), LO2 (human normal cells), and HLF (human embryonic lung fibroblast cells) were examined.