PTPRC and cancer: While DAPI staining tended to show similar proportions of viable and dead cells as trypan blue exclusion (Fig. 4A), Annexin-V co-staining revealed that the majority of CD45-negative DAPI-negative cells (i.e. “viable cancer cells”) were Annexin-V-positive, and thus in early apoptosis (Fig. 4B, lower right quadrant).