There are 4 different subtypes of PK in mammals to meet the specific energy needs of different tissues.[27] As a splice variant of PKM1, PKM2 has been discovered in embryonic cells, adult stem cells, and various tumor cells.[28] PKM2 is directly related to metabolic reprogramming and inflammation of cancer, and its high expression level has adverse effects on tumor growth and prognosis.[29]. This evidence concerns the gene PKM and neoplasm.