PECAM1 and neoplasm: Moreover, PS-acet.-STAT3, but not PS-unacet.-STAT3 or PS-STAT3-K685R peptide, effectively inhibited STAT3 phosphorylation (Supplemental Figure 5D), transcriptional regulation (Supplemental Figure 5E), and tumor progression (proliferation marker Ki-67 and angiogenesis marker CD31; Supplemental Figure 5F).