STX1A and squamous cell carcinoma: First, in contrast to studies which identified Stx of Shigella dysenteriae in association with the nuclear envelope of butyric acid-sensitized epidermoid carcinoma cells [60], and Stx1 and Stx2 in nuclear fractions of human hepatoma cells [63], we did not find OMV-delivered Stx2a in the nuclei of HBMEC.