ABCC1 and telomere syndrome: Thus, endogenous P-gp and MRP-1 expression was qualitatively and retrospectively evaluated by immunochemistry in a subset of 52 high-risk advanced STS tumors of limbs or trunk wall obtained from 328 patients enrolled in an international randomized trial [22], and positive immunoreactivity for P-gp was observed in 28 cases (53.8) and for MRP-1 in 8 cases (15.4%) (Table 1).