In support, PKM2 inhibition using shikonin (a natural naphthoquinone extract from Lithospermum erythrorhizon, purple gromwell) increased the rate of apoptosis and induced the cleavage of caspase-3, caspase-8, and caspase-9 in human gastric cancer cells (HGC-27) [123]. This evidence concerns the gene PKM and gastric cancer.