To further investigate the effects of the newly synthesized compounds on the process of apoptosis we decided to measure their impact on various caspases as evidence of intrinsic (caspase 9) or extrinsic (caspase 8, 10) pathways of programmed cell death by applying flow cytometry analysis after 24 h treatment of MCF-7 breast cancer cells with novel 4-thiazolidinone derivatives and reference drug doxorubicin hydrochloride. This evidence concerns the gene CASP8 and breast carcinoma.