Complex sentence: HeLa cells have also been used to study canine distemper virus' ability to induce apoptosis in cancer cell lines, which could play an important role in developing treatments for tumor cells resistant to radiation and chemotherapy.
Split into simpler sentences: HeLa cells have also been used to study canine distemper virus'ability to induce apoptosis in cancer cell lines. This virus' ability to induce apoptosis could play an important role in developing treatments for tumor cells resistant to radiation and chemotherapy.