CRLF2 and acute lymphoblastic leukemia: To further address the potential link between high CRLF2 expression with high-risk markers and poor outcome in adult ALL without CRLF2 rearrangement, we analyzed transcription factor motifs in the promoter region of CRLF2. As we expected, many core Ikaros binding motifs (GGGA) were identified in the promoter region of CRLF2 (Figure 2A).