SMAD4 and cancer: Point mutation of well-studied genes such as p53 affected the expression of pathways such as MAPK signaling, p53 signaling, WNT, apoptosis, cell cycle across 18 tumor types; mutations in PTEN with changes in expression of p53 signaling in six tumor types, PIK3CA affecting the expression of multiple pathways such as ERBB signaling, MTOR, JAK-STAT, and VEGF signaling across 10 cancer types; and point mutations in SMAD4 in colon cancer affected WNT signaling.