The invention relates to cysteine containing peptides of the structure XXCCXXXXXXXCXXXCXXXXXXQXXCXXXCXCXXXXXXXCXXXXXX, of the structure XXCCXXXXXXXCXXXCXXXXXXXXXCXXXCXCXXXXTXXCXXXXXX and of the structure XXCCXXXXXXXCXXXCXXXXXXXXXXCXXXCXCXXXXXXXXCXXXXXX, wherein X, independently of one another, represents any naturally occurring amino acid, as well as to nucleic acid sequences encoding said peptides, to vectors comprising said sequences, as well as to pharmaceutical compositions containing said peptides and their use as pharmaceutics, particularly for the treatment of cancers.