Increased SRF and MRTFA binding at predicted sites during primary human megakaryopoiesis. Anti-SRF (A) and anti-MRTFA (B) ChIP-PCR results are shown as percentages of input, for the same sites as in Figure 5. Exon 4 of SNRPN was used as a negative control (n = 3). Mean ± standard deviations. Filled triangles represent significant difference between monocytes and early Mks, empty triangles represent significant difference between monocytes and mature Mks, and asterisks represent significant difference between early (CD41⁺CD42⁻) and mature (CD41⁺CD42⁺) Mks. Significance assessed via 1-tailed paired Student t tests (P ≤ .07).