QSOX1 and neoplasm: To prove that suppression of QSOX1 protein expression was responsible for loss of tumor cell invasion, we performed a rescue experiment in which recombinant human QSOX1 (rhQSOX1, generously provided by Dr. Colin Thorpe) was added to shQSOX1-MCF7, shQSOX1-BT549 and shQSOX1-BT474 cells during the invasion assay.