Unfortunately, after publication of this article [1], it was noticed that corrections to the legends of Figs. 1 and 2 were not correctly incorporated. The correct legends can be seen below.

The original article has also been updated.

Figure 1 Binding and blocking properties of LY3300054. Panels a–c: 96-well plates were coated with recombinant human (a), cynomolgus (b), or murine (c) PD-L1-Fc fusion protein (100 ng/well each). Bound LY3300054 was detected using HRP-conjugated anti-human Fab antibody and addition of chromogenic substrate (OD at 450 nm). 96-well plates were coated with 100 ng/well of recombinant PD-1 (d) or B7-1 protein (e), then incubated with a mixture of biotin-conjugated PD-L1 and either LY3300054 or human IgG1 antibodies. Plate bound PD-L1 was detected using HRP-conjugated streptavidin and addition of chromogenic substrate (OD at 450 nm). In all experiments, each data point is the average of two replicates. Data (a-e) are representative of multiple independent experiments

Figure 2 Identification of LY3300054 epitope residues in human PD-L1. Panel a: CLUSTALW multiple sequence alignment of domain 1 of human (hu), canine (ca), and murine (mu) PD-L1 and hu-PD-L2 to identify the LY3300054 species specificity anchors on hu-PD-L1. Underlined is the human PD-1 6 Å binding site on hu-PD-L1 (according to PDB: 4ZQK (26602187)). An alignment position is marked with (*) if both mu-PD-L1 and ca-PD-L1 substitutions differ from the hu-PD-L1 sequence. An alignment position is marked with (:) if either the mu-PD-L1 or ca-PD-L1 substitution differs from the hu-PD-L1 sequence. Panel b: Position N63 on human PD-L1 is a specificity anchor for LY3300054. Canine-to-human mutation K63 N (▲) rescues the ELISA binding of LY3300054 to canine PD-L1. Like wild type ca-PD-L1-Fc (●), canine-to-human mutant N69H (△) does not bind LY3300054