Studies of calbindin-D28k mRNA in control and RA-pretreated D283 medulloblastoma cells at various times (3-24 h) after treatment with 4 micrograms/ml actinomycin D indicated that the half-life of calbindin-D28k mRNA was significantly increased in the presence of RA, suggesting regulation of calbindin-D28k mRNA stability by RA.