BMP4 and colorectal carcinoma: First, we required SNPs to show association with CRC at P<1×10−4 under the allelic or Cochran-Armitage tests; this was a less stringent threshold than that used in our previously-reported hypothesis-free GWA studies [1], [2], [3], reflecting the fact that GREM1, BMP4 and BMP2 were strong candidate susceptibility genes.