CD44 and breast cancer: A study by Bourguignon et al. in ovarian cancer (SKOV-3) and breast cancer (MCF-7) cells, demonstrated 500 kDa HA interacts with CD44 to promote formation of a complex between CD44, Nanog and signal transducer and activator of transcription 3 (STAT-3) which promotes SOX2, REX1 and MDR1 expression, cell growth and resistance to doxorubicin and paclitaxel [67].