GRP75/Mortalin and Calreticulin are measurable in muscle biopsies from human SMA patients. (A) Representative fluorescent western blots on quadriceps femoris muscle biopsy samples from an SMA patient (type II/III) and an age-matched non-SMA control showing levels of GRP75/Mortalin, Calreticulin and Ponceau (loading control). (B,C) Bar charts showing expression levels of GRP75 and Calreticulin in human SMA patient muscle biopsies compared with controls. Data are shown for each individual patient (black and white bars to the left of the dashed line; error bars show variability between two independent measurements taken from that individual’s biopsy), as well as pooled mean for each patient group (right of the line; ± standard error of the mean; n = 6 measurements for each group, two independent measurements from each patient biopsy). (B) GRP75 levels showed a trend towards increased expression in SMA patients, but this difference did not reach statistical significance (ns, not significant; P > 0.05, unpaired, two-tailed t-test). (C) Calreticulin levels were significantly increased in SMA patient muscle (*P < 0.05, unpaired, two-tailed t-test).