Moreover, an inducible NOTCH3 knockdown system was established in 5–8 F R cells and conditional knockdown of NOTCH3 by doxycycline (Dox) significantly inhibited tumorsphere formation of the cells upon PTX treatment (Fig. 2F), while overexpression of NICD3 in 5–8 F P cells or another chemosensitive NPC cell line S18 cells remarkably promoted the tumorsphere formation capability in the presence of PTX (Fig. 2G, H). Here, NOTCH3 is linked to nasopharyngeal carcinoma.