  We compute the transverse single spin asymmetry in light hadron production
$p^\uparrow p\to hX$ and $p^\uparrow A\to hX$ including the gluon saturation
effect in the unpolarized nucleon/nucleus. In the forward (large-$x_F$) region,
the dominant contribution comes from the so-called derivative term associated
with the soft gluonic pole. This leads to the cancellation of nuclear effects
in $A_N$ which can be tested at RHIC. We also show that the soft fermionic pole
disappears in the saturation environment.
