SOX2 and myeloid leukemia: In contrast, motifs corresponding to lineage-specific transcription factors were selectively enriched near TSSs specifically transcribed in the appropriate cell types: GATA motifs were found in myelogenous leukemia K562 cells (Shimizu et al. 2008); SOX2, RFX, and OCT4 (POU5F1):SOX2 composite motifs were confined to H9 embryonic stem cells (Poletti et al. 2015); AP1 binding sites were common to epithelial colon cancer cell line HCT116 and K562 cells; and the CTCF motif was enriched in HCT116 cells (Fig. 4B).