  We propose a modified Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the
summation of large $\ln(1/x)$, $x$ being the Bjorken variable, which contains
an extra dependence on momentum transfer $Q$ compared to the conventional BFKL
equation. This $Q$ dependence comes from the phase space constraint for soft
real gluon emissions in the derivation of the BFKL kernel. The modified
equation gives a slower rise of the gluon distribution function with $1/x$ for
smaller $Q$, such that the predictions for the structure functions
$F_{2,L}(x,Q^2)$ involved in deep inelastic scattering match the HERA data.
These results are similar to those obtained from the
Ciafaloni-Catani-Fiorani-Marchesini equation, which embodies both the $\ln Q$
and $\ln(1/x)$ summations. The reason that the conventional BFKL equation can
not be applied to the low $Q$ (soft pomeron dominant) region is supplied.
