ERCC1 and colonic neoplasm: Protein expression of 12 markers (MGMT, TOPO1, TOP2A, ERCC1, TUBB3, EGFR, TS, PGP, PTEN, RRM1, TLE3 and PD-1) was significantly different in rectal tumors when compared to left- or right-sided colon tumors, or both.