This enhanced tumor growth persisted when low levels of SMAD4 expression were enforced, however, in the presence of BMP4, the time required for 468-GIL tumors expressing SMAD4 to reach 400 mm3 was notably longer (60 days) compared to that for the SMAD4-null tumors (40 days) (Fig. S3d). Here, BMP4 is linked to neoplasm.