PIK3CA and colorectal carcinoma: However, when specifying PIK3CA mutations, the responding cell line (DLD1) and CRC patients (#3, #8) harbored the same PIK3CA exon 9 mutations, whereas intermediate responders and non-responders carried the same PIK3CA exon 20 mutations (HCT116, LS174T, RKO cell lines, and recurrent tumor, primary tumor or metastases of CRC cases #2, #14, #16).