Abundant SERBP1 expression is associated with low PAI-1 protein level in Western blot analysis. SERBP1 protein expression was investigated in extracts of cryoconserved human breast cancer tissues with low (n = 8) and high (n = 8) levels of protein PAI-1 by using Western blot analysis. Extracts with low PAI-1 protein levels (number: 1-3) were associated with intense SERBP1 expression by trend and vice versa high PAI-1 protein levels (number: 4-6) correlated with low SERBP1 expression. Differences between the respective groups were statistically not significant (P = 0.281). β-actin showed a relatively homogenous protein loading in the investigated lysates.