Relationship between overexpression of ras p21 oncoprotein and K-ras codon 12 and 13 mutations in Turkish colorectal cancer patients - AKKİRPİK, Mustafa; ÇELİKEL, Çiğdem Ataizi; DÜŞÜNCELİ, Fikret; SÖNMEZ, Özgür; GÜLLÜOĞLU, Bahadır M.; SAV, Aydın; ÖZER, Ayşe (Turkish Journal of Gastroenterology, 2008)