Fig. 2.

Elevated levels of soluble PD-L1 in culture media after stable overexpression of transmembrane PD-L1. PD-L1-GFP, PD-L1-M/F, or GFP alone, were stably overexpressed in MCF10A, SUM159, SUM149, MDA-MB-231, and BT549 cells. a PD-L1 overexpression was confirmed by Western blotting using cell lysates and anti-PD-L1 antibody (E1L3N). Endogenous PD-L1 is not detectable at this exposure time. GAPDH is a gel loading control. b Concentrations of sPD-L1 in conditioned media were measured by ELISA. Values are means ± SD from three replicate measurements, normalized to equal protein concentration in all cell lysates. P value was determined by one-way ANOVA, followed by Tukey’s multiple comparisons test. Results are representative of three independent experiments