STAB2 and anemia (phenotype): Here, we show that BM-SEC genetically engineered to specifically express a constitutively active mutant allele of Ctnnb1 using the Stab2-iCreF3 driver mouse line (Stab2-iCreF3tg/wtCtnnb1(Ex3)fl/wt) exhibit aberrant sinusoidal differentiation and cause lethal anemia due to a block in terminal erythroid differentiation.