GNRH2 and breast cancer: To analyze the effects of GnRH-II antagonist treatment on induction of apoptosis in GnRH-I receptor-negative (GnRH-I receptor knockdown) human breast cancer cells in comparison with the GnRH-I receptor-positive (wild-type) human breast cancer cells, GnRH-II antagonist-induced loss of mitochondrial membrane potential (ΔΨ) was measured (Figure 1a).