(
A) Workflow of data normalization. (
B) Local normalization (window size 9 × 9). (
C) Extrapolation of background noise distribution. Noise distribution of
N2 is mirrored from distribution of
N1. Standard deviation (SD) was calculated based on distribution
N (Lower panel). (
D) Distribution of Z scores of all proteins on a microarray. Z = 3 was selected as the cutoff in our study to identify the positives. The Z scores of some methylated DNA-binding proteins identified previously (
Spruijt et al., 2013) are below our cutoff, while KLF4's Z score for one DNA motif is >6.