PI3-kinase inhibition prevents retinoblastoma hyperphosphorylation in confluent PASMC exposed to high serum concentrations.

<p>Human PASMC attained confluence in low (0.2%) serum and were maintained in low serum for seven days. Cells were then exposed to 0.1% or 5% serum in the presence or absence of LY294002 or wortmannin and cell lysates harvested 24 hours later for protein analysis. Representative Western blot is shown. [pRB: hypophosphorylated retinoblastoma; ppRB: hyperphosphorylated retinoblastoma].