try these for starters - I think one has them as ints, the other as strings:
/cmap/projects/GEO_deposition/2017-01/combined_matrices/GSE70138_Broad_LINCS_Level2_GEX_n345976x978.gctx
/cmap/projects/M1/DATASETS/GEO/matrices/GSE92742_Broad_LINCS_Level3_INF_mlr12k_n1319138x12328.gctx
--DL