si156 does not reduce the viability of normal human primary cells. (A) The knockdown of the M2 isoform of pyruvate kinase mRNA by si156 is confirmed in SF372 human adult skin fibroblasts and human umbilical vein endothelial cells (HUVECs). Primers were designed to amplify total PKM, PKM1 only, or PKM2 only. Duplicate biological samples were collected 48 h after transfection with 5 nM siRNA, and each sample was assayed in technical triplicate. (B) Lysates were collected from SF372 and HUVE cells 48 h after transfection with 5 nM siRNA. Blots were probed with antibodies targeting either total PKM or PKM2. NT, no treatment. Vinculin was used as a loading control. (C) Relative cell viability was determined after six days. SF372 and HUVE cells were transfected with 5 nM siRNA at 0, 48, and 96 h. Transfections were performed in technical quadruplicate on two independent occasions. NT, no treatment. Error bars denote standard deviation.