Our data also indicate that increasing the free Ca2+ concentration in the pipette did not increase the KCa3.1 activity in HNSCC T cells, thus indicating that CaM deficiency, and not a reduction in Ca2+ sensitivity due to other mechanisms such as changes in CaM and/or channel phosphorylation, is responsible for low KCa3.1 activity in HNSCC T cells (Fanger et al., 1999). This evidence concerns the gene KCNN4 and head and neck squamous cell carcinoma.