To analyze whether ECs could also induce VE-cadherin expression in breast cancer cells in a paracrine manner, independently of direct cell–cell contact, we treated MCF7 and MDA-MB-231 with HUVEC supernatant (collected after 72 h culture), and tested their VE-cadherin content and changes after 24, 48, and 72 h by Western blots (Figure 1E and Figure S2A). Here, CDH5 is linked to breast carcinoma.