Quantification of SHIP1 expression in monokine-stimulated primary human CD56⁺ NK cells. (A) CD56⁺ primary human NK cells were first incubated for 18 hours with medium containing either IL-12 (10 ng/mL) and/or IL-18 (100 ng/mL), and then quantified for SHIP1 (A) mRNA by real-time RT-PCR and (B) protein by Western blot. The relative levels of SHIP1 protein, as determined by densitometry, are indicated above the blot and expressed as densitometric units relative to the control lane (“none”), which is arbitrarily set at 1.00. (C) The graph summarizes the data of densitometric analysis of 3 primary donors. This experiment is representative of at least 3 such experiments performed with similar results.