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