Adult podocyte cell lines were cloned by limiting dilution from glomerular cultures of the “immortomouse” (Jat et al., 1991 (link)) harboring a transgene for a thermosensible variant of the SV-40-T–antigen, which is under the control of the H-2Kb-promotor, whose activity can be increased by γ interferon. The cellular origin of the cloned cell lines from the podocyte lineage was proven by the detection of the Wilm's tumor gene product (WT-1), which in the adult kidney is an exclusive marker of podocytes (Mundlos et al., 1993 (link)). Cells were propagated at 33°C in RPMI 1640 containing 10% FCS (Boehringer Mannheim, Mannheim, Germany), 100 U/ml penicillin (GIBCO BRL, Karlsruhe, Germany), 100 μg/ml streptomycin (GIBCO BRL), and 10 U/ml recombinant mouse γ interferon (Sigma Chemical Co., Munich, Germany) to induce synthesis of the immortalizing T antigen. Subcultivation was done with trypsin at 37°C after cells had reached confluence. Cells were passaged after 1:5 dilution. To initiate differentiation, cells were thermoshifted to 37°C and maintained in medium without γ interferon (Mundel et al., 1997 ).