Updated project metadata. Phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) is a lipid second messenger produced by class I phosphoinositide 3-kinases (PI 3-kinases) phosphorylation of phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2). Although typically associated with the plasma membrane, it is now appreciated that PI(3,4,5)P3 generation also occurs in the nucleus to regulate a variety of biological functions. Using a PI(3,4,5)P3-specific GST-GRP1PH domain reporter and immunofluorescence microscopy, we have found that DLD1 and SW480 colorectal cancer (CRC) cells exhibit pronounced nuclear staining of PI(3,4,5)P3. To characterise the nuclear PI(3,4,5)P3 interactome in DLD1 and SW480 cells, we performed affinity pull-down experiments on nuclear extracts using a ω-amino analogue of phosphatidylinositol 3,4,5 -triphosphate (PI(3,4,5)P3 immobilised onto Affi-gel10 beads. Gel fractionation and LC/MS-MS analysis was performed to reduce sample complexity and increase resolution, with samples run on a LTQ Orbitrap Elite mass spectrometer. DLD1 and SW480 cells were both analysed in four independent biological replicates. A protein was considered a member of the nuclear PI(3,4,5)P3 interactome if it was identified in at least two experiments (with at least two peptides, FDR of 1%) in both cell lines, yielding a total of 1237 unique proteins (representing 1103 genes for DLD1 and 1001 genes for SW480 cells).