Isolation of SBP-SMC2 from formaldehyde cross-linked cell populations. Silver stain analysis of SBP tagged SMC2 and GFP isolated from uncross-linked (left panels) and cross-linked cell populations (right panel). SMC2 SBP isolated from cells cross-linked with formaldehyde show integrity of the SMC2-SMC4 heterodimer with no significant increase in background bands. Note the GFP-SBP also appears purified to near homogeneity from cross-linked cells but bound no significant amount of DNA. Only sample isolated from the SMC2-SBP purified cross-linked complexes contained significant amount of DNA, suggesting the SBP tag will be highly amenable for enriching DNAs of chromosomal proteins.