  We present recent results of single-spin asymmetry $A_N$ measurements in
$\pi^0$ inclusive production. Asymmetry was measured in $\pi^-p$ and $pp$
interactions at 40 and 70 GeV correspondingly. Significant asymmetry was
observed in the polarized target fragmentation region. The results are in
agreement with "universal threshold" of single-spin asymmetry.
