HaCaT, and its three retrovirally c-Ha-ras-transformed subclones, A5, II-4 and RT3 (abbreviated as ras-HaCaTs in the text) that exhibit benign, invasive and malignant phenotypes, respectively, were cultured as 3D monocultures and co-cultures with fibroblasts. After hypotonic lysis of the cells, the insoluble proteins were analysed by LC-MS/MS.