Mouse embryo multiple-tissue northern blot and mouse adult multiple-tissue northern blot filters were purchased from Clontech Laboratories (Palo Alto, CA). The filters were hybridized with the 32P-dATP labeled DNA fragment of Mcoln1 coding region corresponding to exon 2 (see above). For the alternative transcript, a probe was generated in the region between exons 12 and 13 with primers 5'-GTGTCCACCACCTGAGAG-3' (forward) and 5'-GAAGTAGCATTCCTGCAGGC-3' (reverse) with an annealing temperature of 62°C. The filters were then hybridized with β-actin probes. Hybridizations and washes were carried out in standard conditions, with the stripping of previously bound probes in between [16].