Fig 5 respectively indicate the alteration of apoptosis maker proteins in human lung cancer A549 and H460 cells cultured with 10–50 μM norcycloartocarpin. The correspondent increase of activated caspase3 (Cleaved caspase-3) and degraded form of its substrate, cleaved PARP, was obviously noticed in the cells treated with 50 μM norcycloartocarpin for 24 h (Fig 5A–5D). Moreover, there was the higher expression of cleaved caspase-9, an initiator caspase in A549 and H460 cells after incubation with norcycloartocarpin at 25 and 50 μM as presented in Fig 5A and 5B, respectively. Here, CASP9 is linked to lung cancer.