  Precision data are presented for the break-up reaction, $^2{\rm H}(\vec
p,pp)n$, within the framework of nuclear-force studies. The experiment was
carried out at KVI using a polarized-proton beam of 190 MeV impinging on a
liquid-deuterium target and by exploiting the detector, BINA. Some of the
vector-analyzing powers are presented and compared with state-of-the-art
Faddeev calculations including three-nucleon forces effect. Significant
discrepancies between the data and theoretical predictions were observed for
kinematical configurations which correspond to the $^2{\rm H}(\vec p,^2$He$)n$
channel. These results are compared to the $^2{\rm H}(\vec p,d)p$ reaction to
test the isospin sensitivity of the present three-nucleon force models. The
current modeling of two and three-nucleon forces is not sufficient to describe
consistently polarization data for both isospin states.
