There seems to be some ambiguity regarding MRC1 and MRC1L1.

If you query BioMart using MRC1 and ask for Agilent probes as an attribute, you get A_23_P12746, as suggested previously. If you query using MRC1L1 you get 2 results: one with A_23_P12746 as a probe, the other a different transcript with no probe.

The gene card for MRC1L1 states that it lies very close to MRC1, on chromosome 10, in a duplicated region.

Searching at UCSC browser throws up 2 UCSC genes named MRC1, close to each other and 4 Refseq genes (2x MRC1, 2x MRC1L1), in apparently identical positions.

Here are the results of the BioMart queries:

Ensembl Gene ID  Ensembl Transcript ID  Agilent WholeGenome  HGNC ID  HGNC symbol      Chromosome Name  Transcript Start (bp)  Transcript End (bp)
ENSG00000120586  ENST00000239761        A_23_P12746          7228     MRC1             10               18098352               18200091
ENSG00000183748  ENST00000331429        A_23_P12746          23403    MRC1L1           10               17851362               17953178
ENSG00000183748  ENST00000457317                             23403    MRC1L1           10               17851362               17896832

This indicates that there are 2 MRC1L1 transcripts and the probe maps to one of them, as well as to the MRC1 transcript.