Figure 1From: Signal transducer and activator of transcription 5 as a key signaling pathway in normal mammary gland developmental biology and breast cancerSTAT5 influences differentiation, survival, and proliferation through alterations in cellular gene expression. After activation by tyrosine phosphorylation (P), STAT5A and STAT5B form homodimers and heterodimers that move into the nucleus, where they can act as transcription factors to influence gene expression. STAT5, signal transducer and activator of transcription 5.Back to article page