Comparative testing of various pancreatic cancer stem cells results in a novel class of pancreatic-cancer-initiating cells

► We tested all known putative pancreatic cancer stem cells (PCSC) markers. ► Cell surface and intracellular markers showed significant variability among cell lines. ► Side population response to confluence, hypoxia, radiation, and gemcitabine was inconsistent among cell lines. ► A novel subpopulation of SP/CD44-CD24-CD326+ cells demonstrated increased tumorigenicity over previously reported PCSC.