1. -11.9 kb -4.2 kb -5.6 kb Gfi1 +/1b neo Gfi1 +/+ Gfi1 +/1b Gfi1 1b/1b Gfi1 +/1b Gfi1 +/+ -11.9 kb - 4.2 kb Gfi1 +/+ Gfi1 +/1b -14 kb - 8 kb B A Gfi1 +/+ Gfi1 +/1b Gfi1 1b/1b Gfi1 (55 kDa) Gfi1b (37 kDa) loading control C Supp. Figure 1

2. Gfi1 +/+ Gfi1 P2A/P2A - 15 kb - 8 kb B Gfi1 +/P2A Gfi1 +/+ - 15 kb - 8 kb Gfi1 +/P2A Gfi1 P2A/P2A Gfi1 +/+ Gfi1 -/- Gfi1 (55kDa) loading control A Supp. Figure 2

3. ∆ Rn cycle 0 5 10 15 20 25 30 35 40 Amplification Plot Gfi1 1b/1b 1.000 E-4 1.000 E-3 1.000 E-2 1.000 E-1 1.000 1.000 E+1 Gfi1 Gfi1b 1.000 E-4 1.000 E-3 1.000 E-2 1.000 E-1 1.000 1.000 E+1 Gfi1 Gfi1b 0 5 10 15 20 25 30 35 40 Amplification Plot Gfi1 +/+ A B Gfi1 Gfi1b GAPDH Gfi1 +/+ Gfi1 1b/1b H 2 O Supp. Figure 3

4. IP: anti Gfi1b We: anti PIAS3 PIAS3 175 83 62 47.5 IP: anti Gfi1b We: anti Gfi1b Input IP anti-GSTIP anti-Gfi1b Gfi1b IgG 83 62 47.5 32.5 Supp. Figure 4

5. Table 1 Differential cell counts of wild type, Gfi1 -/-, Gfi1 P2A/P2A and Gfi1 1b/1b mice Supp. Table 1  significant