Expression of Src-like adapter protein mRNA is induced by all-trans retinoic acid

By using a differential display method, specific bands were selected from ladder PCR products derived from ATRA-dependent differentiated U937 cells, in comparison with those of untreated U937. By screening the cDNA library of ATRA-dependent differentiated U937 cells with one of the PCR products, we cloned the src-like adapter protein (SLAP). Northern blot analysis of U937 cells with or without ATRA treatment indicated that the SLAP mRNA was clearly induced by ATRA. The induction was inhibited by the addition of cycloheximide, indicating that ATRA acted indirectly through synthesis of other proteins. The SLAP mRNA was induced in HL60 and NB-4 but not in K562 or THP-1. Interestingly, these cells in which SLAP mRNA was induced by ATRA all showed ATRA-dependent cell differentiation. The relationship between SLAP and cell differentiation is unclear, but SLAP may transduce a signal for cell differentiation.