A change in Ca2+ sensitivity of CDI could presumably occur via STIM1-driven change in the conformation of the C-terminus, which harbors several acidic residues that could bind Ca2+ and which are located in close vicinity to residues L273 and L276 that are critical for STIM1 binding (Muik et al., 2008; Navarro-Borelly et al., 2008). Here, STIM1 is linked to clostridium difficile infection.