NGB and breast cancer: In this context, reported data sustain a critical function of extracellular released NGB proving that (i) NGB is extracellularly released by breast cancer cells in both in vivo and in vitro conditions, (ii) H2O2 treatment promotes NGB secretion from breast cancer cells, (iii) extracellular NGB acts in reducing ROS generation under oxidative stress condition and in promoting cell resistance against chemotherapeutic treatment, and (iv) effects of extracellular NGB on breast cancer phenotype completely overlap with those reported for oxidative stress induced homotypic conditioned medium.