Increasing the volume of rSK1 or rSK2 expressing virus added to neuronal cultures increased the relative expression of mRNA of the specific gene delivered without affecting the other: infection of 1 × 105 rat hippocampal cultures with 0.2 μl and 0.5 μl rSK1-HA lentivirus increased rSK1 relative expression by 60 and 200-fold, respectively, while infection with 0.2 μl and 0.5 μl of rSK2-Myc lentivirus increased rSK2 relative expression by 10 and 40-fold, respectively (data not shown). This evidence concerns the gene MYC and infection.