CD44 and renal cell carcinoma: To elucidate whether spheroid cells could enrich cells expressing cell markers associated with renal progenitor cells or RCC stem cells, spheroid cells and adherent cells were stained for CD44, CD133,CD105, Oct4 and Nanog by immunofluorescent (Fig. 3a), flow cytometry (Fig. 3.b1,b2), reverse transcription PCR (RT-PCR) (Fig. 3.c1,c2) and Western blot (Fig. 3.d1,d2).