HK2 and head and neck squamous cell carcinoma: While a slight, but not significant, increase in extracellular lactate production was detected in HK2-silencing HNSCC cells (Supplementary Figure 4), immunofluorescence staining analysis implied that lamellipodia-like F-actin (dot-lined in Figure 3C) was predominantly found in HK2-deficient HNSCC cells in comparison with control cells those contain more evident filopodia-like protrusions.