  The strangeness production in heavy ion collisions was proposed to be probes
of the nuclear equation of state, Kaon potential in nuclear medium, strange
quark matter and quark-gluon plasma, etc. However, to act as reliable probes,
proper understanding of the basic ingredients for the strangeness production,
such as $pp \to pK^+\Lambda$, $pp \to pp \phi$ and $pp \to nK^+\Sigma^+$ is
necessary. Recent study of these reactions clearly shows that previously
ignored contributions from the spin-parity $1/2^-$ resonances, $N^*(1535)$ and
$\Delta^*(1620)$, are in fact very important for these reactions, especially
for near-threshold energies. It is necessary to include these contributions for
getting reliable calculation for the strangeness production in heavy ion
collisions.
