Finally, to exclude SP toxicity, we performed a mitochondrial respiration-based cell viability screen in two unrelated cell lines, a human embryonic kidney cell line with overexpression of SSTR2 and the cAMP probe (HEK-GS/SSTR2_HA, also utilized as the sensor cells in the targetability bioassay) and a human breast carcinoma cell line (MCF7). Here, SSTR2 is linked to breast carcinoma.