Figure 7: Generation of SBA-labeled tubules versus cell clustering by the interference of the tubulogenic signal between the mineralocorticoid receptor and heat shock proteins. (a) Histochemistry on cryosections demonstrated that renal stem/progenitor cells without hormone administration did not exhibit SBAlabel. (b) Formation of extended SBA-labeled cell clusters is observed after treatment with aldosterone (1 x 10-7 M) in combination with geldanamycin (3,6 x 10-6 M). (c) Application of aldosterone (1 x 10-7 M) in combination with radicicol (2 x 10-6 M) led to cell clustering, while minimal formation of SBA-labeled tubules was oberserved. Both (d) quercetin (2 x 10-4 M) and (e) KNK 437 (1 x 10-4 M) in combination with aldosterone (1 x 10-7 M) produced numerous SBA-labeled cells within extended clusters, while only single tubules were found. (f) Formation of intact tubules was observed after aldosterone (1 x 10-7 M) administration, while occurrence of cell clusters was lacking.