Transcription factor that binds to 5'-TTGAATTGA-3' elements in the promoter region of target genes. Functions as repressor of the ecmB gene. Regulates the differentiation of prestalk cells during development. Monomer, in the absence of tyrosine phosphorylation. Homodimer, or heterodimer with another family member, when tyrosine phosphorylated. Cytoplasmic in growing cells. Translocated into the nucleus in response to cAMP-induced tyrosine phosphorylation. Nuclear at the tight mound stage and in the upper, prestalk region of tipped aggregates and in cells at the tip of the slug. Subject to crm1-dependent nuclear export. Constitutively expressed with a slight increase during the tight mound stage (at protein level). Detected at very low levels in growing cells and aggregates up to the loose mound stage. Highly expressed in tipped aggregates and in the Mexican hat stage. Expressed at lower levels in early and late culminants and in fruiting bodies. Tyrosine phosphorylated in response to cAMP. Not tyrosine phosphorylated in growing cells. Tyrosine phosphorylation is first detected at the tight mound stage, continues throughout the slug stage and early culmination, and starts to decrease at mid-culmination. Barely detectable in fruiting bodies. Cells are hypersensitive to the chlorinated hexaphenone DIF. They form slugs, but there is little or no stalk cell differentiation. After several days of developmental arrest very small spore masses appear that are supported by columns of apparently undifferentiated cells. Belongs to the transcription factor STAT family.