In Vitro: Sigma1 inhibition by IPAG causes the autolysosomal degradation of PD-L1 in PC3 (hormone-insensitive prostate cancer) and MDA-MB-231 (triple-negative breast cancer) cell lines and reduces the levels of functional PD-L1 on the surface of the cells. IPAG treatment produces a mean of 100±8 μg per 106 cells. IPAG can inhibit cell proliferation. Treatment with IPAG decreases cell mass. IPAG treatment suppresses phosphorylation of translational regulator proteins p70S6K, S6, and 4E-BP1.