Primary hepatocytes were isolated from 12-week-old male Prom1+/+ (WT) or Prom1-/- (KO) mice, serum-starved and stimulated with glucagon. J. The cAMP concentration 10 minutes after glucagon stimulation (10 nM) was determined using the cAMP assay kit in the absence or presence of 10 μM IBMX (n = 3 mice/group). 