The involvement of p38 MAPK signaling pathway in the induction of apoptosis of RIN cells under the influence of PA and Sn. RIN cells were cultivated in the absence (medium) or presence of 125 μM PA and/or 40% Sn. For apoptosis detection, RIN cells were treated with PA and Sn in the absence or presence of an inhibitor of p38 MAPK signaling – SB202109 (40 μM) for 6 hours, and subsequently stained with AnnV/EtD-III (A). Alternatively, RIN cells were treated with PA and/or Sn for 1 hour, then cell lysates were made before western blotting for p38 MAPK and phosphorylated p38 (p-p38) (B, C). Mean values +/- SD of values obtained in 5 (A) and 3 (B) individual experiments with similar results are presented, or a representative western blot (C). *p < 0.05 represents a statistically significant difference relative to the cultures grown in medium without additional treatment (A, B) and to the cultures treated with SB (A).