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The LHCb Collaboration announced two pentaquark-like structures in the$J/\psi p$ invariant mass distribution. We show that the current information onthe narrow structure at 4.45 GeV is compatible with kinematical effects of therescattering from $\chi_{c1} p$ to $J/\psi p$: First, it is located exactly atthe $\chi_{c1} p$ threshold. Second, the mass of the four-star well-established$\Lambda(1890)$ is such that a leading Landau singularity from a trianglediagram can coincidentally appear at the $\chi_{c1} p$ threshold, and third,there is a narrow structure at the $\chi_{c1}\,p$ threshold but not at the$\chi_{c0} p$ and $\chi_{c2} p$ thresholds. In order to check whether thatstructure corresponds to a real exotic resonance, one has to measure theprocess $\Lambda_b^0\to K^-\chi_{c1} p$. If the $P_c(4450)$ structure exists inthe $\chi_{c1} p$ invariant mass distribution as well, then the structurecannot be just a kinematical effect but is a real resonance, otherwise, onecannot conclude the $P_c(4450)$ to be another exotic hadron. In addition, it isalso worthwhile to measure the decay $\Upsilon(1S)\to J/\psi p \bar p$: anarrow structure at 4.45 GeV but not at the $\chi_{c0} p$ and $\chi_{c2} p$thresholds would exclude the possibility of a pure kinematical effect.

How to reveal the exotic nature of the P_c(4450)