PKM and neoplasm: In Bluemlein et al. [4], the authors demonstrated for the first time that the PKM2 protein was the dominant isoform of PKM by quantitative mass spectrometry in both normal and tumor tissues and this finding was validated by our analysis of the TCGA RNA-Seq data In our research, we confirmed that PKM1 significantly declined in many types of tumors, which was consistent with previous studies but not the results of Bluemlein et al [2–4].