JAK3 and neoplasm: By contrast, analysis of different tumor samples revealed the absence of γc chain staining (P<0.01) with a very faint JAK3 protein expression (P<0.01) while, no significant differences (P>0.05) in the expression of the IL-2Rβ chain were observed between normal and tumoral tissues therefore confirming the results obtained in vitro in primary cultures of normal and cancer cells.