EP300 and breast cancer: The expression of translocated P300 in laryngeal squamous cell carcinoma (LSCC) tissue is much higher than that in adjacent normal tissue and is associated with advanced stage and poor prognosis.178 Missense point mutations in p300 are found in colorectal adenocarcinoma, gastric adenocarcinoma and breast cancer with quite low incidences.186,187 Rare inactivating mutations in CBP and PCAF have only been identified in cancer cell lines but not primary tumors.188 Based on these findings, we hypothesize that the differences between cell lines and primary tumors cannot be ignored.