Abstract: The present invention relates to tumor targeting units comprising a peptide sequence X—R—Y—P—Zn, or a pharmaceutically or physiologically acceptable salt thereof. The invention further relates to tumor targeting agents comprising at least one targeting unit according to the present invention, directly or indirectly coupled to at least one effector unit. The present invention further relates to diagnostic or pharmaceutical compositions comprising at least one targeting unit or at least one targeting agent according to the present invention, and to the use of targeting units or targeting agents according to the present invention for the preparation of a medicament for the treatment of cancer or cancer related diseases, especially for the treatment of non-small cell lung cancer or its metastases.