CD44 and cancer: Similarly, CD44-IR700 NIR-PIT caused significant cell death and dramatic reduction of tumour growth in TNBCs overexpressing the CD44 antigen, a cancer stem cell (CSC) marker frequently found in aggressive breast carcinomas, as described by Jin et al in their in vitro and in vivo experiments employing athymic Balb/c (nu/nu) mice (Jin et al., 2016).