spib is necessary for primitive myeloid differentiation. spib-depleted embryos show absence or reduced expression of mpo, spi1, and mmp7 but not cebpa. (A-O) WMISH and (P,Q) RT-PCR analysis on spib ATG and e1i1 morphants. ATG*** is a 3-mismatch ATG morpholino. (P) spib ATG morpholino reduces but does not eliminate all spib transcripts, (Q) whereas spib e1i1 morpholino eliminates functional spib mRNA at 10 ng. (A-F) Severe reduction on the number of spib- and mpo-expressing cells and (J-O) marked absence of spi1 and mmp7 expression on spib morphants. (G-I) Under the same experimental conditions, cebpa-expressing cells are not affected. All embryos are shown in lateral views with anterior to the left. The number of representative embryos is shown at the bottom right corner of each panel.