CD44 and breast cancer: In addition, co-injection of patient derived breast cancer cells with CD10+GPR77+ CAFs promoted tumor formation as well as the proportion of bCSCs upon serial translation of breast cancer cells [183], and binding of the ECM protein hyaluronan (HA) to the stem cell receptor CD44 resulted in Nanog mediated activation of stem cell specific genes such as Sox2 and Rex1 in breast cancer cells.