Fig. 2. Transient upregulation of p110 and p110ß mRNAs during in vitro differentiation of human keratinocytes. (A) Samples of 20 µg total RNA from adult human keratinocytes grown in primary culture under differentiation-promoting conditions were analyzed by northern blotting using cDNA probes specific for p110 and p110ß. ß-actin or involucrin probes were hybridized as a loading control or to monitor differentiation, respectively. (B) Western blot analysis verifies transient upregulation of p110 protein upon differentiation. The blot was re-incubated with antibodies against phosphorylated Akt (Ser473), PTEN, involucrin, keratin 10 (K10), and ß-actin to verify upregulation of differentiation markers (involucrin, keratin 10) or as a loading control (ß-actin).