BCL2 and cancer: These NGs were also conjugated with anticancer DOX or to a pro-apoptotic Bcl-2 siRNA by GSH-responsive redox-sensitive spacer, 3-(2-aminoethyl) dithiopropionic acid (AEDP), to obtain a controlled release mechanism specific for cancer cells through FR targeting in a co-culture system of HeLa (a positive FR, cancer cell line) and NIH3T3 cells (a negative FR, fibroblast cell line) [86].