NRP1 and breast carcinoma: Another study indicated that overexpressing NRP-1 caused chemoresistance in pancreatic cancer cells through the MAPK signaling pathway (25), Similarly, we observed an increase in the expression levels of soluble and focal NRP-1 using ELISA and western blot, respectively, in an MDA-MB-231 breast cancer cell-chemoresistant model (4xAC+4xPAC) generated in our lab (Figures 5A,B).