['The expression of all eleven PKC-isoforms in clear cell RCCs (ccRCC) and in the corresponding normal renal tissue was quantified. A possible association of PKC-isoforms with histopathological parameters was examined.', 'Proteins were isolated from tumor and normal tissue of 43 patients with ccRCC. Expression of PKC-isoforms were quantified by Western blot analysis.', 'In both, ccRCCs and the corresponding normal renal tissue, all PKC-isoforms apart from PKC gamma and theta were detectable. Striking associations between PKC-isoforms and histopathological parameters were observed: (i) a 3-fold increase in PKC eta of grade 3 and 4 versus grade 1 and 2 tumors (p = 0.025), (ii) a decrease of PKC alpha in tumor versus normal tissue of 18% (p = 0.020) and (iii) a 20% increase of PKC zeta in grade 3 and 4 versus grade 1 and 2 tumors (p = 0.092).'] Is protein kinase C eta associated with progression of renal cell carcinoma ( RCC )?