  We discuss the unintegrated parton distribution functions (UPDFs) introduced
by Kimber, Martin and Ryskin (KMR), which are frequently used in
phenomenological analyses of hard processes with transverse momenta of partons
taken into account. We demonstrate numerically that the commonly used
differential definition of the UPDFs leads to erroneous results for large
transverse momenta. We identify the reason for that, being the use of the
ordinary PDFs instead of the cutoff dependent distribution functions. We show
that in phenomenological applications, the integral definition of the UPDFs
with the ordinary PDFs can be used.
