PECAM1 and breast cancer: In the same study, this correlation was not observed in TNBC and HER2+ BC subtypes, and TMEM structures in BC can be identified and quantified in formalin-fixed paraffin-embedded tissue by using triple immunostaining for the three different cell types recognized in direct physical contact, and precisely, Mena-overexpressing tumor cells (pan-Mena antibody), macrophages (CD68), and endothelial cells (CD31).