Abstract: The invention relates to nucleic acid molecules encoding insecticidal proteins of the Cry family, derived from Bacillus thuringiensis, exhibiting cytotoxic activity against cancer and/or tumor cells of humans and/or animals, but not against normal cells. The invention also provides proteins and compositions of proteins of the Cry family, derived from the bacteria Bacillus thuringiensis, that exhibit cytotoxic activity preferably against cancer cells of humans and/or animals, without affecting the normal cells. The Cry proteins of the invention do not exhibit any hemolytic activity, nor do they belong to the parasporin group. The invention also relates to methods for treating cancer and/or tumor cells of humans and/or animals, and for preventing metastasis, using insecticidal Cry proteins of Bacillus thuringiensis.