PIK3CA and colorectal carcinoma: Although the isogenic cell colonies with homozygous Y508F mutations on PIK3CA locus could not be able to generate, heterozygous mutation of p110α Y508 already inhibited the proliferation, colony formation abilities of CRC cells in vitro and the growth of xenograft tumors in vivo (Fig. 3A-3D and S3A-S3E).