QSOX1 and neoplasm: In non-tumor fibroblasts, expression of QSOX1 was correlated with the quiescent stage, Go, of the cell cycle and overexpression of QSOX1 was shown to protect MCF7 cells for ROS mediated apoptosis [21], this led us to hypothesize that a shQSOX1-mediated decrease in cell proliferation could be the result of abnormal regulation of the cell cycle, an increase in apoptosis or the result of autophagosome formation.