The screening of a tiling siRNA library reveals sequences that can discriminate between the M1 and M2 isoforms of pyruvate kinase. (A) The sequences of the M1 and M2 isoforms of pyruvate kinase are shown. Mismatches are highlighted in yellow. (B) The viability of HCT116 cells for each member of the siPKM2 library is shown relative to the no treatment control. Cells were transfected with 5 nM siRNA at 0, 48, and 96 h and were assayed after 6 d. Transfections were performed in technical quadruplicate on two independent occasions. The three most active siRNA sequences are highlighted in red. NT, no treatment.