Any process that stops, prevents, or reduces the frequency, rate or extent of the phosphorylation of a serine residue of a STAT (Signal Transducer and Activator of Transcription) protein.
Synonyms:
narrow_synonym:
down regulation of serine phosphorylation of STAT3 protein; downregulation of serine phosphorylation of STAT3 protein; inhibition of serine phosphorylation of STAT3 protein; negative regulation of serine phosphorylation of STAT3 protein