Figure 6. Elevation of cSrc activity and/or levels in ERα^– primary breast cancers.

(A) Cryopreserved breast tumors were lysed, ERα status was verified by Western blot, and cSrc kinase activity was assayed. Equal loading was confirmed by β-actin. Blots are representative of 22 ERa⁺ and 18 ERa^– tumors. (B and C) ERα and Src protein levels were quantitated by RPPA in 101 primary breast cancers as described in Methods. (B) Histogram distribution of log Src protein levels (arbitrary units) rounded to nearest log for HR⁺ (ERα⁺ and/or PR⁺) and HR^– (ERα^– and PR^–) cancers. (C) Dot plot of Src and ERα protein values (expressed as log values, arbitrary units) in all cancers (P = 0.008).