Sentence: In the present study , we investigated the effect atorvastatin , celecoxib and tipifarnib in combination on proliferation and apoptosis in Panc-1 sphere-forming cells .
Drug combination annotation:
[{'class': 'POS', 'spans': ['atorvastatin', 'celecoxib', 'tipifarnib'], 'is_context_needed': True}]