Northern blot analysis of poly(A)+ RNA from various human tissues. Multiple-tissue Northern blots containing approximately 2 μg of poly(A)+ RNA (Clontech, Palo Alto, Calif.) were probed with the 2.9-kb 32P-labeled R-receptor cDNA. S, spleen; LN, lymph node; T, thymus; PBL, peripheral blood lymphocytes; BM, bone marrow; FL, fetal liver; H, heart; B, brain; Pl, placenta; Lg, lung; L, liver; SM, skeletal muscle; K, kidney; P, pancreas.