GRP and breast cancer: Heidari and co-workers used a peptide based on a universal binding sequence (Lys-Gly-Gly-Cys-Asp-Phe-Gln-Trp-Ala-Val-bAla-His-Phe-Nle) to target breast cancer in vitro and in vivo with gold nanorods for photothermal therapy [42] as well as imaging [43], and they pointed out its several advantages in comparison to native bombesin sequence, such as overcoming the issues related to receptor heterogeneity in tumors and ameliorating renal clearance due to the negatively charged hydrophilic aspartic acid residue.