miR-144 and miR-451 in zebrafish erythroid development. (A) Genetic pathway connecting the mutation meunier (mnr), the microRNAs miR-144 and miR-451, and the miR-451 target gata2. (B) Models of the biologic impact of this genetic pathway on erythroid maturation, in wild-type, and in various perturbed scenarios. Gray arrows indicate reduced (↓) or increased (↑) net level of activity at steps of the genetic pathway. Gray crosses (X) indicate the level of block in the pathway in the individual scenarios. For the net biologic outcome of the genetic pathway on repression of erythroid maturation, a dotted line indicates a normal (ie, wild-type) level of repression, and a continuous line indicates a stronger-than-normal repressive effect. TB-MO indicates target-blocking morpholino oligonucleotide.