Most chemotherapeutic agents are able to trigger apoptosis in HEK293T cells; we have used etoposide, and assayed apoptosis using fluoresgenic vector with inserts of caspase specific peptides. If an indicated caspase is activated, the insert would be cleaved, and the vector restores to fluorescence emission. I think that the signals became clear within 10 hrs. Induction by TNF alpha +cyclohemixide could be even efficient, or you could use an agonistic anti-FAS antiboby. Jurkat T cells are used as control for FAS/APO1 stimulation. The monolayers become blebbing around 2 hrs.