When compared the survival of TICs with bulk cancer cells using the mitotic-quiescence properties of TICs to retain specific dyes, such as PKH26, in culture16, PKH-positive cells survived in spheres compared with PKH-negative cells at 15 days of CCS spheroid culture, which were positive for TUNEL and cleaved caspase 3 (Fig. 2f). Here, CASP3 is linked to cancer.