YSY01A is a proteasome inhibitor that can suppress cancer cell survival by inducing apoptosis ( Apoptosis ). Its IC 50 values are 51.0 nM for HEK293T, 9.2 nM for A549, 5.2 nM for MCF-7, 8.9 nM for MGC-803, and 35.4 nM for PC-3M cells. Additionally, YSY01A eliminates constitutive STAT3 signaling by downregulating gp130 and JAK2 in human A549 lung cancer cells. YSY01A holds promise for research in the field of cancer therapy.