Serum response factor pathway. Extracellular signals activate the MAPK/RAS/ERK or the RhoA signaling pathways. TCFs or MRTFs are recruited to SRF and modulate SRF-mediated transcriptional activity. SRF regulates β2 integrin inside-out activation and trafficking. DIAPH1, Diaphanous 1; ERK, extracellular signal-regulated kinase; MKL1, megakaryoblastic leukemia 1; MRTF, myocardin-related transcription factor; RAS/RAF, rat sarcoma virus oncogene; RhoA, Ras homolog family member A; SRF, serum response factor; TCF, ternary complex factor.