PI-1840 is a potent and selective chymotrypsin-like (CT-L) inhibitor for with an IC50 value of 27 nM. PI-1840 inhibits cell proliferation and arrest cell cycle at G2/M phase. PI-1840 induces apoptosis and induces autophagy. PI-1840 induces the accumulation of proteasome substrates p27, Bax, and IκB-α[1][2].