SPACI score report for 2x4n in ASTRAL 2.06:

PDB Entry: 2x4n
SPACI score: 0.35
AEROSPACI score: 0.35

Experiment type: XRAY
Resolution: 2.34
R-factor: 0.2004
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -0.383
WCK2 WHAT_CHECK Ramachandran: -1.804
WCK3 WHAT_CHECK Chi angles: -1.368
WCK4 WHAT_CHECK Backbone: 0.891

Note: Here are links to pages about PROCHECK and WHAT_CHECK.

Here is the full WHAT_CHECK report on this protein (linked from the WHAT_CHECK site).