CD24 and breast cancer: It should also be noted that as Mvt1 cell line naturally comprises two sub-populations of both CD24-positive and CD24-negative cells, the regulation mechanism of CD24 expression in these cells may be different than other mammary tumor cells that are characterized as “pure” CD24-expressing cells, such as Met1 cell line, in which ATF5-KD did not affect the cell surface expression of CD24 (data not shown).