Band 4.1a to 4.1b ratio. (A) Silver-stained SDS–polyacrylamide gel electrophoresis (PAGE) of erythrocyte membrane proteins. Samples were isolated form 5 wt and 6 tg6 individuals and the part of the gel containing bands 3 through 4.2 labeled according to Steck²¹  is shown. (B) Quantification of the band 4.1a to 4.1b ratio by densitometry revealed an increased ratio in tg6 red cell membranes, which is typical for senescent erythrocytes. Means (± SD); n = 5-6; ***P < .001.