ANXA5 and cancer: To assess the induction of cancer cell death, cells were treated with PpIX and stained with propidium iodide (PI) or Annexin V. Compared with untreated control cells, PpIX-treated EHEB cells showed a significant increase in the PI positive population (late apoptosis), from 20.73 to 94.45% and in the Annexin V positive population (early apoptosis), from 21.74 to 39.59% (Fig. 2d) after 24 h.