Double immunohistochemistry of human breast cancer tissues showed that p97 expression was significantly higher (p = 3.827 × 10−6) in CD44+/CD24− cells than in the non-CD44+/CD24− cells (i.e., CD44−/CD24−, CD44−/CD24+, and CD44+/CD24+ cells) (Fig. 1b–d and Table S1). Here, CD44 is linked to breast cancer.