We have found that some tumor infiltrating lymphocytes in colorectal cancer (CRC) tumor expressed low intensity of FOXP3 with flow cytometry assays, resulting in the presence of certain amount of tumor infiltrating FOXP3lo cells in subpopulation of CRC tumor tissues. To clarify different gene expression paterns between CRC tumors with high FOXP3lo cell infiltration and without these cell infilrtraion, we performed microarray analyses with total mRNA extracted from whole tumor tissues with high FOXP3lo cell infiltration (n=2) and low FOXP3lo cell infiltration (n=2). Comparison of gene expression profiles revealed that genes involved in immune responses and inflammation were significantly up-regulated in tumor with high FOXP3lo cell infiltration. Overall design: Total RNA from tumor tissues with high FOXP3lo cell infiltration (n=2; cOSK109, cOSK111) and low FOXP3lo cell infiltration (n=2; cOSK93, cOSK237) was isolated with RNeasy Mini Kit (Qiagen) and subjected to microarray analysis (Human Gene 2.0 ST Array, Affymetrix). Obtained raw data was normalized by the robust multi-array average algorithm (RMA) (R 2.15). Gene ontology (GO) biology process are described in 15180 genes. T-statistics was calculated by comparing these tumor types..