CD44 and colorectal carcinoma: CD44 expression of CRC cells was evaluated by immunofluorescence (Fig. 3b), a significantly up-regulation of CD44 was observed when CRC cells were treated by CC-CAFs-CM, the result was confirmed by flow cytometry analysis (Fig. 3c), and when 50% diluted CC-CAFs-CM was used to treat tumor cells, expression of CD44 was decreased compared with 100% CM which indicated that the CD44 up-regulation induced by CC-CAFs-CM was dose-dependent.