Chloroform extract from Cucurbita ficifolia fruit, due to modifying the activity of proteins: p53 (tumour suppressor protein responsible for monitoring and controlling the genetic integrity of cells), FAS (cell surface death receptor), FADD (FAS-associated death domain; apoptosis signal mediator), Bax and Bak, and subsequent modulation of caspase-3, caspase-8, and caspase-9 genes expression levels, showed an apoptosis-inducing effect in MCF-7 breast cancer cells. This evidence concerns the gene FAS and breast carcinoma.