SMAD4 and pancreatic neoplasm: Another group found that in human pancreatic cancer cell lines, that loss of deleted in pancreatic cancer 4 (DPC4), homologous to Smad4, expression disrupts TGF-β signaling, reducing the ability to inhibit cell growth and regulate target genes like p21waf1, which may contribute to unchecked cell proliferation in pancreatic cancer [88].