GRP and neoplasm: Doxorubicin has been chemically conjugated to a number of other peptides, including cell penetrating peptides (CPP) [125,126], tumor homing peptide Lyp-1 [127], RGD peptides [40], somatostatin [128,129,130], and bombesin/gastrin-releasing peptide (BN/GRP) [128,131,132], and broadly studied.