CD47 and neoplasm: Note that human CD47 expression is absent in these immunocompromised mice, any human CD47-specific antibodies will only bind to tumor cells in these models, regardless of whether they have pH-dependent binding ability or not; and antibodies with higher binding affinity (BC31M5), but not better pH-dependence (BC31M4), are more likely to have better antitumor activity; however, human CD47 is ubiquitously expressed on healthy cells in patients.