Fluctuations in the CD99 levels in EWS cells are associated with specific transcripts [19] and microRNA [20] expression profiles, but also with actin remodeling [21], the spatial redistribution of critical regulators of cancer aggressiveness, such as zyxin [19], Rock2 [21], and ERK1/2 [22], and the modulation of intracellular signaling pathways including Src signaling [23]. Here, CD99 is linked to cancer.