Table 1 Isoforms of STAT3

STAT3α

Canonical activator of transcription; Key roles during STAT3 promoting cancer development

The longest isoform

92

Alternative splicing

[2]

STAT3β

Repressor of STAT3; Higher DNA-binding affinity; Higher stability of STATs dimers

Loss of C-terminal (Ser727 missing)

83

Alternative splicing

[2]

STAT3γ

Regulation of neutrophil survival

Loss of C-terminal (Tyr705 and Ser727 missing)

72

Proteolysis

[3,4,5]

STAT3δ

Activated during neutrophils and granulocyte maturation (early stage)

Loss of C-terminal (Tyr705 and Ser727 missing)

64

Proteolysis

[3]

STAT3ε

Played no role in cardiogenesis

N-terminal containing; Shares overlapping homology with STAT3α

50

Caspase-3 cleavage upon K685-acetylation

[6]

STAT3ζ

Adaptor of the ErbB4-p38γ signaling pathway during the cardiomyocyte differentiation

C-terminal containing; Shares overlapping homology with STAT3α

45

Caspase-3 cleavage upon K685-acetylation

[6, 7]