Figure 5. (A) SREBP1 and ABCA1 protein expression levels. Data are the mean ± SEM. **p < 0.01 (unpaired t-test). (B) Protein-protein interaction network of periostin and important factors in aging. Pathways are indicated by dotted lines based on clustering of the proteins according to their biological processes using STRING. ABCA1, ATP binding cassette transporter 1; AKT1, AKT Serine/Threonine Kinase 1; CCL5, C-C Motif Chemokine Ligand 5; CDH1, Cadherin 1; CERK, Ceramide Kinase; COL1A2, Collagen Type I Alpha 2 Chain; FN1, Fibronectin 1; HMGCR, 3-Hydroxy-3-Methylglutaryl-CoA Reductase; HMGCS2, 3-hydroxy-3-methylglutaryl-CoA synthase 2; PLA2G4A, Phospholipase A2 Group IVA; POSTN, Periostin; SLC2A2, Solute Carrier Family 2 Member 2; SMPD2, Sphingomyelin Phosphodiesterase 2; SREBF1, Sterol Regulatory Element Binding Transcription Factor 1; TGF, Transforming growth factor.