We also conducted a primary breast tumor tissue microarray (TMA) study and observed a correlation of CD44 and CD81 expression across tumor subtypes (TNBC, HER2, luminal A/B) as well as an upregulated expression of CD44/CD81 in TNBC in comparison to luminal A/B (Figure 4—figure supplement 2A–D). Here, CD81 is linked to breast neoplasm.