As shown in Fig. 4A and B, and Tables 1 and 2, the major components of Lac were identified as the laccaic acids A, B, C and E, by interpretation of the MS and MS2 with relevant references.18–21 Importantly, the crude fractions of the laccaic acids significantly suppressed the IFN-γ-induced PD-L1 expression on both M14 and A2058 melanoma cells (Fig. 4C). Here, CD274 is linked to melanoma.