Figure 4.

PL induces the activation of hypoxia-inducible factor 1-alpha (HIF-1α) and activation of signal transducer and activator of transcription 3 (STAT3) pathways. (A) Western blot analysis of proteins extracted from cells cultured in the absence of FCS and presence of PL for different times. Proteins extracted from cells cultured in hypoxia (1% O₂) in serum-free medium at 4 h were analyzed as control. (B) Quantification of HIF-1α, phosphorylated STAT3 (pSTAT3), and Cyclin D1. Density values are normalized to actin and expressed as fold increase (n =3), at 32 h, only two samples were analyzed. * p < 0.05, ** p < 0.01.