Fig. 4

Protein levels and pyruvate kinase activity in HAP1 and ΔSHMT2 cells. Homozygous loss of SHMT2 reduces protein levels and activity of pyruvate kinase in HAP1 cells. A PKM1 and PKM2 protein levels and B pyruvate kinase activity in HAP1 cells and ΔSHMT2 cells. PKM1 and PKM2 protein levels were normalized to GAPDH, and densitometry was performed using ImageJ. Two-way ANOVA with Tukey’s post hoc analysis was used to determine media by genotype interaction and main effects of media and genotype with a statistical significance at p < 0.05. Levels not connected by the same letter are significantly different. Data represent means ± SD values, n = 2–5 per group. GAPDH, glyceraldegyde-3 phosphate dehydrogenase; PKM1 and PKM2, pyruvate kinase M1 and M2 isoforms