CACNA1S and infection: Therefore, in order to investigate if calcium homeostasis would also regulate CACNA1S expression during M. tb infection, using specific bio-pharmacological agents we inhibited internal calcium release and external calcium influx prior to stimulation with Rv2463 or infection with live M. tb. Internal calcium release was blocked using treatment with TMB8, a calcium antagonist that blocks intracellular calcium release [50], while external calcium influx was blocked using EGTA.