SCN5A and cancer: More importantly, the availability–voltage relationship was also significantly shifted to a more depolarized potential in shSCN4B cells compared with shCTL cells (V1/2–availability were −80.6±1.6 mV (n=22) and −86.3±1.6 mV (n=18), respectively, P=0.016, Student's t-test; Fig. 5b), suggesting that even though there were less NaV1.5 channels at the plasma membrane, they might be more active at the membrane potential of cancer cells (comprised between −30 and −40 mV) through an increased persistent window current.