part_of part of part of cell surface receptor protein serine/threonine kinase signaling pathway SMAD protein signal transduction https://github.com/geneontology/go-ontology/issues/23773 An intracellular signaling cassette that starts with the activation of a SMAD protein, leading to the formation of a complex with co-SMADs, which translocates to the nucleus and regulates transcription of specific target genes. GO:0060395 Note that the upstream receptor and its ligand regulate the pathway (and are not part of the SMAD pathway), since it is an intracellular signaling pathway. biological_process intracellular signaling cassette